Problem Solving Skills for Mathcounts Competitions

Feedback and Communication => Feedback and Communication => : yongcheng3315 February 23, 2012, 11:41:03 AM

: 50 Matcounts lectures pdf files
: yongcheng3315 February 23, 2012, 11:41:03 AM
On Wed, Feb 22, 2012 at 3:23 PM, <@gmail.com> wrote:

    Dear Teacher Chen,
    
    I was one of your 50 MathCounts Lectures students. Recently I took the 2012 AMC 10B. After checking the solutions pamphlet and comparing it to my answers, I got a 130.5. Thanks for helping me achieve this with your 50 Lectures! I really appreciate it!
    
    Sincerely,
    
    M.
__________________________________________________________________________________________________

from:    [email protected]
to:    <@gmail.com>
date:    Thu, Feb 23, 2012 at 12:38 PM
subject:    Re: AMC 10B Score
mailed-by:    gmail.com



Thank you for letting me know that. You did a great job with a score of 130.5. I am really proud of you.  Keep working hard for AIME !


Dr. Chen
: 50 lectures pdf files
: yongcheng3315 February 27, 2012, 02:37:26 PM
On Mon, Feb 27, 2012 at 2:45 PM, <@yahoo.com> wrote:

Dear :
 
We had Chapter round Mathcounts last Saturday.  My daughter's team won 4th place and could move to state competition.
Her score:Sprint: ...,  target: 16.

The competition is tough, but she did her best.  

I really want to thank you for so many good information and the state round solution, which help her a lot.   I saw her improvement during the practice, and look forward to next year.

BTW, everytime she did some problem which take a lot of time, she asked me whether Jane's mom had a better method;-)
 
 

: 50 lectures pdf files
: yongcheng3315 March 01, 2012, 07:26:25 AM
from: @cox.net
to: ourmathcounts <[email protected]>

date: Fri, Feb 10, 2012 at 9:16 AM
subject: Re: 50 lectures pdf files

Thank you. I also bought 20 mock test the other day. Is there anyway to reach solution of the book. It is really good book and some of the questions are really tough.


Thank you

Sent from my iPhone
: 50 lectures pdf files
: yongcheng3315 March 01, 2012, 07:58:25 AM
from: @nmsu.edu
to: [email protected]

date: Thu, Dec 22, 2011 at 4:29 PM
subject: 50 Mathcounts Lectures

Dear Guiling:

I just purchased your "50 Mathcounts Lectures". I prefer to receive them as electronic files via e-mail so that my son can start to work on your lectures right away. Thank you and Happy Holidays!

Sincerely,
: Re: 50 lectures pdf files
: yongcheng3315 March 01, 2012, 08:19:07 AM
from: [email protected]
to: "mymathcounts.com" <[email protected]>

date: Fri, Dec 16, 2011 at 10:49 PM
subject: Re: 50 lectures vs 20 and 20 more problems books

I bougth these two books plus 20 Mock from Amazom.com, and they are fantastic! 
I am wondering if you have any advise or suggestion for AMC12 and AMIE study materials besides Art Of Problem Solving.
 
Happy Holidays!
: Re: 50 lectures pdf files
: yongcheng3315 March 01, 2012, 08:34:06 AM
from: [email protected]
to: "mymathcounts.com" <[email protected]>

date: Wed, Nov 23, 2011 at 1:47 AM
subject: question on weighing items

 
My daughter and I are learning the 50-lectures with very slow pace.  I am glad we have the books and it provides us very good guidance.
 
One question we need your help - do you have more detailed solutions for Problem 1 (9 balls) and Problem 6 (5 coins) of Chapter 1 Logical Reasoning?  We are not sure of how to understanding "the smallest number of balance scale weighings" and "what is the least number of weighings" in each problem.
 
You don't need to hurry to answer my question.  I understand it is holiday season and everybody is busy ......

Happy holiday! 

Regards,
: Re: 50 lectures pdf files
: yongcheng3315 March 01, 2012, 08:45:02 AM
from: @hotmail.com
to: [email protected]

date: Tue, Nov 1, 2011 at 2:32 PM
subject: RE: 50 lectures volume 3

Thank you so much for the great help! I have received one file, you mentioned two files, please let me know if I have anything missing! It is hard to say how much I appreciated, right now, my daughter has many activities right now, if she get some free time, I really would like her to register your mathcounts program!
    Best to you & your wonderful family!
: Re: 50 lectures pdf files
: yongcheng3315 March 13, 2012, 07:00:27 AM
Sent to: A 2015 on: March 12, 2012, 07:11:19 PM » Quote Reply Remove  

--------------------------------------------------------------------------------
Thanks Yongcheng,

My son got the first place in chapter competition. I really want to say thanks to you.
Since last summer, he learned a lot from your 50 lectures and mathcount training.

He will go State on March 23. Do you have any suggests for him?

He already did at least 10 years questions. But half of questions can not be solved by himself. He is in 6th grade right now. Some questions like possibility, algebra is too hard for him.

Thanks.
________________________________________________________________________________________________

Message subject:    Re: advice needed for state mathcounts
From:    
Sent:     7:46 pm
To:    



Sure, no problem.

Sprint:

Sprint was always my favorite round. At nationals, I missed two Targets but still managed to get into the Countdown because of my sprint score (it's also the first tie-breaker). So Sprint is important.

In the actual competition, I didn't follow any of the weird "start at the end" or "skip questions you can't get right away" strategies. I just blazed right through them. I guess part of this was based on my ability; I could do all of the problems (except maybe 1 or 2), it was just about how much time I spent on them. I found it most useful to finish all of the problems I started, unless I really was stuck, which didn't happen much. Anyway, my advice (assuming you get 20+ in practices) is to just go in order. The last ones are the hard ones, and they usually take longer, but all of the problems are worth the same amount, so it's best to make sure you do the easy ones.

At State, the biggest thing I can say about Sprint is to use the problem number to your advantage. If it's a #7, and the best you can come up with is like 20 separate cases, there's probably an easier way. This is also true only slightly of Team, and not at all of Target. On Sprint, the first few should get you warmed up, and I would expect to get half way in around 1/3 the total time.

To prepare, I would just find a hundred or so Sprint problems and work through them all in one or two sittings. Just doing problem after problem after problem helps you for Sprint.

Target:

Target has always been my worst round, except at Regionals. The key with Target is to get an answer quickly, and then check it in every way you know. I always solved both problems (or at least got an answer) and then went back and checked them. Occasionally, I checked the first before moving on, but you're right the first time a lot.

Make sure to read the problems at least twice and remember all of the little tricks they like to throw in, like converting square inches to square feet (x144), and anything else they might come up with.

To be honest, I don't know how to prepare for Target without just doing old tests.

That's all I can think of right now. Confidence is a great booster too, almost as much as sugar and caffeine.

No, I'm serious - lots of sugar helps you think faster. But that's coming from someone who never gets stressed, so it might be different for you. But I always had a pop or two and any donuts they had before the contests.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Message subject:    Re:  mathcounts help
From:    
Sent:     7:08 pm
To:    

Hello ,

I apologize for taking so long to get back to you. For some reason, I didn't receive an e-mail notification about your private message, and so I've neglected to check my PM inbox until now. Thank you for your kind words of support.

As for MathCounts advice, where do I begin. First, and perhaps most importantly, you must remember that MathCounts is just a competition, and there are more important things in the world. Also, while it's definitely nice to win or place highly at Nationals, the AMCs are *more* (loosely used term here) important.

Memorization is important, but how you apply your memorization is more important. For example, perhaps you know the binomial theorem. But do you know why it works exactly the way it does? Same logic goes for most every theorem or formula you memorize.

Avoiding careless mistakes is a very personal issue and difficult to deal with. Everybody has different things that cause them to make mistakes, and I suppose somehow identifying the situations in which you are prone to making mistakes is the best first step toward reducing the number of these mistakes you make. It's very difficult not to make careless errors; I personally never managed to get 8/8 on the Target Round at either State or Nationals in either of my years.

Finally, preparation in general consists of doing lots of problems. I remember doing every State and Nationals round in MathCounts history, as well as every Warmup, and Workout. However, simply doing 10,000 problems is not a guaranteed formula for success. Even if you get 29/30 on a sprint round, it's extremely important that you focus on the problem you missed, and understand exactly why you weren't able to solve it (didn't know a formula, didn't see a different approach, made a careless error, etc.). In fact, even if you get 30/30 or 46/46, unless you know you solved every problem in the fastest and most efficient possible way, you still have room to improve.

Good luck in your future endeavors,
Albert
: Re: 50 lectures pdf files
: yongcheng3315 May 08, 2012, 08:47:29 AM
from:    [email protected]
to:    [email protected]
date:    Mon, May 7, 2012 at 7:55 PM
subject:    Re: 2012 Summer American Math Competition Training Program

First of all, I would like to appreciate all your time and efforts on providing math materials for the kids.   My son is a 6th grader.   I ordered your 50 MathCounts lectures for him last summer.   He has studied some of the chapters when he has time since then.   He won the 3rd place individual on the state competition at his grade among 349 students at his grade nine days ago.  He has learned a lot from your lectures.   It looks like you also have made some revisions per my observation through the forum.   Can you email me a newest greatest revised version?   

I’m interested in registering my son for AMC 10 and 12 training course this year.   I’ll do it shortly.  By the way, where can I buy “Eleven Years (1990-2000) MathCounts Solutions” in PDF?

_____________________________________

from:    mymathcounts.com [email protected]
to:    [email protected]>
date:    Tue, May 8, 2012 at 9:04 AM
subject:    Re: 2012 Summer American Math Competition Training Program

Thank you for contacting me and let me know your child's math activity.
 
First congratulations to him and to you!
 
Thank you again for your interests in our AMC Summer program.

The newest revision for 50 Mathcounts Lectures is here:
 
http://www.mymathcounts.com/Forum/index.php?board=86.0

"Eleven Years (1990-2000) MathCounts Solutions " links are here:
 
Chapter:

http://www.mymathcounts.com/Chapter-Training-Group.php

State:
 
http://www.mymathcounts.com/State-Training-Group.php
: Re: 50 lectures pdf files
: yongcheng3315 June 15, 2012, 12:42:21 PM
from:    [email protected]
to:    "mymathcounts.com" <[email protected]>
date:    Thu, Jun 14, 2012 at 10:35 PM
subject:    Re: Eleven Years Mathcounts Chapter Solutions
mailed-by:   

Thank you so much for your books. I wish I know your site and books early. Your books is definitely exellent products for Mathcounts! In addition to the 3 books I purchased today. I want to purchase another great books "50 MathCounts Lectures (Volume 1,2,3)" (most recent printed) hard copy books and pdf files. Could you give some discount for this package? :-) I am definitely a fan of your books now.
 
Let me know, I will paypal the money to you. Thanks!
: Re: 50 lectures pdf files
: yongcheng3315 July 09, 2012, 06:39:14 PM
from:    YJia [email protected]
to:    ourmathcounts <[email protected]>
date:    Mon, Jul 9, 2012 at 3:48 PM
subject:    Re: 50 Mathcounts lectures V1

Do you have Volumn 2, 3...  50 Mathcounts Lectures? My son almost finished Volumn 1 and found it very helpful.
 
Thanks,
 
C
__________________________________________________________

from:    ourmathcounts [email protected]
to:    YJia [email protected]
date:    Mon, Jul 9, 2012 at 8:33 PM
subject:    Re: 50 Mathcounts lectures V1

Thank you very much for using our book! Yes we have volumes 2 and 3. Below is the link:

Good luck!

 http://www.mymathcounts.com/50-Mathcounts-lectures.php


: Re: 50 lectures pdf files
: yongcheng3315 August 09, 2012, 11:21:35 AM
On Tue, Jul 16, 2012 at 11:53 AM, Rama
wrote:

Hello,

My daughter and I are diligently working on the 50 math counts
lectures. The content is great. We are almost through Volume 1.

________________________________________________________
On Tue, Jul 31, 2012 at 11:53 AM, Rama
>> wrote:

>>>
>>> Can you pls explain the solution in the forum. We finally got the
>>> answer, but our solution looked bit complex.
>>>
>>> Thanks
>>> Rama
_______________________________________________
On Thu, Aug 9, 2012 at 10:50 AM, ourmathcounts <[email protected]> wrote:
>
> ABD is a right triangle with the sides of 6-8-10. So DB = 10 and OB = 5.
>
> Triangle ABD is similar to triangle OBE.
> So AD/AB = EO/OB.
>
> 6/8 = EO/5. Therefore EO = 15/4 and EF = 2 EO = 15/2 = 7.5.
>
>
> See a similar problem in our book "Twenty More problem solving skills"
> Chapter 17 Folding Papers with 7 different methods.
>
> Good luck!
_________________________________________________________

from:    Rama
to:    ourmathcounts <[email protected]>
date:    Thu, Aug 9, 2012 at 12:06 PM
subject:    Re: 50 MathCounts Lectures/Chapter 29/Problem 8

Thank you.

We haven't ventured in to the 'twenty' problems books yet.

We really enjoy working through the problems, will continue to provide
feedback on any minor issues we find.

Great collection!

Rama
: Re: 50 lectures pdf files
: yongcheng3315 August 09, 2012, 11:24:20 AM
On Thu, Jul 26, 2012 at 11:50 AM, Y Wang  wrote:

    My son could not figure out #14 on lecture 50, could you please provide me solution? Do you have solution files for all other lecture problems?Thanks Ye
    Problem 14
    A four-digit number is chosen at random from all four-digit number. Express as a common fraction the probability that the number is divisible by 2,3,4 and 5.(mathcount competitions).
_________________________________________________________________________________________

From: ourmathcounts <[email protected]>
To: Y Wang
Sent: Thursday, July 26, 2012 12:16 AM
Subject: Re: mathcount lecture-question

Thanks for asking. Sorry I do not have a solutin file.
 
Hope the following will help.
 
Good luck!
 
Solution:

There are 9*10*10*10 = 9000 4-digit numbers.

The number desired should divisible by lcm (2,3,4,5) = 60.

The first 4-digit number divisible by 60 is 60* 17 = 1020.

The last one is 60*166 = 9960.
There are 166 - 17 + 1 = 150 such numbers.

The probability is 150/9000=1/60
____________________________________________
from:    Y Wang
reply-to:   
to:    ourmathcounts <[email protected]>
date:    Mon, Jul 30, 2012 at 5:52 PM

Thank you so much! Y
subject:    Re: mathcount lecture-question
: Re: 50 lectures pdf files
: yongcheng3315 August 27, 2012, 06:24:29 AM
from:    [email protected]
to:    mymathcounts.com
date:    Fri, Aug 24, 2012 at 6:02 PM
subject:    Math counts training

 Hi ,

I have bought you Mathcounts books from Amazon.  3 volumes of 50 lectures series as well as 11 years of state competition solutions.  They have been excellent preparatory materials for my son.  Appreciate your effort in preparing the materials.

Last year you conducted training for mathcounts, do you plan to do that this year? If so please let me know.

We were not aware of AMC training you had started in summer -  otherwise we would have signed up.  Can you please include us in your mailing list?  Thanks once again.

Thank you for your great efforts in math area - your books are making a strong influence in my son's life.

Best Regards,
V
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 November 29, 2012, 12:55:59 PM
from:    F. W. [email protected]

to:    yongcheng3315 <[email protected]>
date:    Tue, Nov 27, 2012 at 11:43 PM
subject:    Re: 美国中学生数学竞赛(AMC8/10/12)的题和解答

老师, 您好!

我人在中国. 暑假其间, 曾从您处购买50 MathCounts lectures (以下是当时的邮购通讯). 溜览了一下美国的初中竞赛题, 挺有收获的. 寒假将近, 我想购买 AMC10/12 lectures 读一读. 还是邮汇到同样地址吗? 多少人民币?

谢谢!
吴Wei
: Re: 50 Matcounts lectures pdf files
: fzhu99 January 02, 2013, 11:20:31 AM
对于我们订阅的读者 for AMC Training Session,
1)有许多typo.
2)我们有一些chapters (e.g.: 29, 39-50) 没有收到,而且file name也比较乱(especially for first 4 chapters)。

能不能审阅、校对、整理后,把所有的50 chapters再一起刊登一次?
Thank you for your consideration.
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 January 02, 2013, 02:56:03 PM
Thanks for the message.

Sorry for the confusion.

To get chapter 39-50, you need to register. The link is as follows:

http://www.mymathcounts.com/American-Math-Competition-Training-Session-%283%29.php

We are reviewing every page of the session 2 (chapter 26-38) right now. When we finish, we will post a copy of the file and send you a copy as well.

Happy New Year!
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 January 26, 2013, 03:47:10 PM
from:    WK <[email protected]>
to:    ourmathcounts <[email protected]>
date:    Fri, Jan 25, 2013 at 10:46 AM
subject:    Re: 50 Mathcounts lectures pdf files

Thanks for the information. I looked through the book and like it. I am running a math enrichment program and would like to use it for the classes. I knew the authors had run a summer program using this materials. Do you have the ppt files to go with the book? If I could use this materials for classes, you book sale will also be promoted. Please let me know. Thanks.

W

: Re: 50 Matcounts lectures pdf files
: yongcheng3315 January 30, 2013, 09:44:06 AM
January 29, 2013, 08:37:21 PM    
Subject: Thank you
From:   jliuee

大大的谢谢!你的书是太好了。从这本书,我女儿在六年级开始好好学数学。

-J


January 30, 2013, 10:43:21 AM
From: yongcheng3315:
 
Thank you so much for purchasing our 50 Mathcounts Lectures books and for the nice words. Please do not hesitate to contact me if I can be more helpful to you. Good luck!
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 04, 2013, 12:22:01 PM
from:    [email protected]
to:    "[email protected]" <[email protected]>
date:    Sun, Feb 3, 2013 at 8:42 PM
subject:    Mathcounts Preparation

Hello,

I have several of your Mathcounts books, and just now, bought the State Preparation package from your website and am awaiting the link to access the material.  Your books are very good!

I have a question for you.  My 7th grader just got First Place in Chapter and wants very badly to try and get to Nationals from State.  What would your advice be for preparation?  Should she prepare using Nationals material or using State material?  I noticed on your website that you mentioned that to prepare for Chapter one should use State material.

Any other tips and advice?  She mostly loses points due to careless errors, and does not have time to check over her work.  Any other advice/input/tips would be greatly appreciated!

Thanks,
Rima


Sent from my iPad

________________________________________________

from:    ourmathcounts <[email protected]>
to:    Rima Lal <[email protected]>
date:    Sun, Feb 3, 2013 at 9:42 PM
subject:    Re: Mathcounts Preparation

Congratulations to your child!

One way to overcome careless mistakes is to do a lot of practice.

Your child needs to work on national problems in order to do good at state. One week before the test she needs to do a set (state sprint and target) of test every day. But do no math the day before the test.


If you need the past national problems, please let me know and I am happy to share with you.


Below are two messages that may be useful for your child. First message was from a boy who was in top 12 nationally and the second one was from a National Champion.

Good luck!

________________________________________________________________________________


Message subject:    Re: advice needed for state mathcounts
From:   
Sent:     7:46 pm
To:   



Sure, no problem.

Sprint:

Sprint was always my favorite round. At nationals, I missed two Targets but still managed to get into the Countdown because of my sprint score (it's also the first tie-breaker). So Sprint is important.

In the actual competition, I didn't follow any of the weird "start at the end" or "skip questions you can't get right away" strategies. I just blazed right through them. I guess part of this was based on my ability; I could do all of the problems (except maybe 1 or 2), it was just about how much time I spent on them. I found it most useful to finish all of the problems I started, unless I really was stuck, which didn't happen much. Anyway, my advice (assuming you get 20+ in practices) is to just go in order. The last ones are the hard ones, and they usually take longer, but all of the problems are worth the same amount, so it's best to make sure you do the easy ones.

At State, the biggest thing I can say about Sprint is to use the problem number to your advantage. If it's a #7, and the best you can come up with is like 20 separate cases, there's probably an easier way. This is also true only slightly of Team, and not at all of Target. On Sprint, the first few should get you warmed up, and I would expect to get half way in around 1/3 the total time.

To prepare, I would just find a hundred or so Sprint problems and work through them all in one or two sittings. Just doing problem after problem after problem helps you for Sprint.

Target:

Target has always been my worst round, except at Regionals. The key with Target is to get an answer quickly, and then check it in every way you know. I always solved both problems (or at least got an answer) and then went back and checked them. Occasionally, I checked the first before moving on, but you're right the first time a lot.

Make sure to read the problems at least twice and remember all of the little tricks they like to throw in, like converting square inches to square feet (x144), and anything else they might come up with.

To be honest, I don't know how to prepare for Target without just doing old tests.

That's all I can think of right now. Confidence is a great booster too, almost as much as sugar and caffeine.

No, I'm serious - lots of sugar helps you think faster. But that's coming from someone who never gets stressed, so it might be different for you. But I always had a pop or two and any donuts they had before the contests.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Message subject:    Re:  mathcounts help
From:   
Sent:     7:08 pm
To:   

Hello ,

I apologize for taking so long to get back to you. For some reason, I didn't receive an e-mail notification about your private message, and so I've neglected to check my PM inbox until now. Thank you for your kind words of support.

As for MathCounts advice, where do I begin. First, and perhaps most importantly, you must remember that MathCounts is just a competition, and there are more important things in the world. Also, while it's definitely nice to win or place highly at Nationals, the AMCs are *more* (loosely used term here) important.

Memorization is important, but how you apply your memorization is more important. For example, perhaps you know the binomial theorem. But do you know why it works exactly the way it does? Same logic goes for most every theorem or formula you memorize.

Avoiding careless mistakes is a very personal issue and difficult to deal with. Everybody has different things that cause them to make mistakes, and I suppose somehow identifying the situations in which you are prone to making mistakes is the best first step toward reducing the number of these mistakes you make. It's very difficult not to make careless errors; I personally never managed to get 8/8 on the Target Round at either State or Nationals in either of my years.

Finally, preparation in general consists of doing lots of problems. I remember doing every State and Nationals round in MathCounts history, as well as every Warmup, and Workout. However, simply doing 10,000 problems is not a guaranteed formula for success. Even if you get 29/30 on a sprint round, it's extremely important that you focus on the problem you missed, and understand exactly why you weren't able to solve it (didn't know a formula, didn't see a different approach, made a careless error, etc.). In fact, even if you get 30/30 or 46/46, unless you know you solved every problem in the fastest and most efficient possible way, you still have room to improve.

Good luck in your future endeavors,
Albert
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 07, 2013, 07:58:21 AM
from:    [email protected]>
to:    ourmathcounts <[email protected]>
date:    Thu, Feb 7, 2013 at 7:46 AM
subject:    Re: 50 Mathcounts lectures pdf files

Hi Y,

My son just won the Chapter mathcounts this past Saturday and he really benefited a lot from studying your materials. Thank you very much. As he was preparing for the upcoming State competition, I was wondering if you can share with us the National problems and solutions for the past 3 years. I have done a lot of search on the internet but was only able to collect 2002-2009 National problems. If you have other materials that are free to share (or available to be ordered), please feel free to let me know. Thanks.

Happy Chinese New Year!

W
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 11, 2013, 08:48:16 AM
from:    [email protected]>
to:    "[email protected]" <[email protected]>,
 
date:    Sun, Feb 10, 2013 at 4:03 PM
subject:    Mathcounts


        Thank you so much for your great help on Mathcounts, my daughter is very benefit from the 50 lectures and she is advanced to the state now! 

        Thank you so much!
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 18, 2013, 12:11:35 PM
Mon, Feb 18, 2013 at 12:18 PM, <[email protected]> wrote:

   
    Comment: Dear Sirs:
    In 50 Mathcounts Lectures v1, Exponents chapter, problem 50 on page 205, which is greater 7^{92} or 8^{91}, could you please guide me to a solution? Or even which Mathcounts Handbook this is taken from so that I can look up the solution?
    My daughter is working on this problem, and we seem stuck.
    Thanks,
    N

_______________________________________________________________________________________________

On Mon, Feb 18, 2013 at 11:39 AM, mymathcounts.com <[email protected]> wrote:

    This problem was from the book Math Circles by Dmitry Fomin. The book does not provide a solution.

    50. Which number is greater: 7^92 or 8^91?

    My solution:

    We know that 8^6 = 262144 and 7^6 = 117649, so 8^6/7^6 > 2 and (8/7)^18 > 8.

    8^91/7^92 = (8^91/7^91)*(1/7) = (8/7)^73*(8/7)^18*(1/7) > 1.

    So 8^91 > 7^92.

    Any better ways are welcome.

    Good luck!
______________________________________________________________________________

From: <[email protected]>
Date: Mon, Feb 18, 2013 at 12:57 PM
Subject: Re: Comparing Exponents
To: "mymathcounts.com" <[email protected]>


Thanks for the quick answer. Outstanding solution. I was able to wring out a solution using binomial expansions, but it's not as clean as your solution. Moreover, the binomial expansion seems a bit too advanced.

Do you know the reference to the problem in Fomin's book?

By the way, do you also have any books regarding SAT English? Or can you recommend what books you used for your's son's training. (In an earlier email, you had mentioned that your son was a Bevan Scholar.)
Thanks,
Nihal

: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 19, 2013, 06:20:42 PM
On Tue, Feb 19, 2013 at 8:07 AM, mymathcounts.com <[email protected]> wrote:

    Thanks.

    The problem is on Chapter 16, page 175 of the book (problem #4).

    As for SAT English, I am not an expert on training it. Sorry I do not have much to say.

    Here is a link with some practice problems:

    http://www.whw.name/index.html


    Good luck!

_________________________________________________________________
from:    <[email protected]>
to:    "mymathcounts.com" <[email protected]>
date:    Tue, Feb 19, 2013 at 11:00 AM
subject:    Re: Comparing Exponents

Thanks for your reply. After I sent the email, I also found it.

By the way, and I know that I have mentioned this earlier too, but your books are awesome. With each chapter, they continue to amaze me even more.

Thanks,
Nihal
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 February 25, 2013, 07:51:56 AM
from:    Y & S S <[email protected]>
to:    myamc10and12 <[email protected]>
date:    Mon, Feb 25, 2013 at 12:12 AM
subject:    RE: AMC & MathCounts

I just ordered the 50 MathCounts Lecures (1,2,3 set) as you suggested.  Once we are done with those, I will order the 20/20 followed by AMC lectures.

Also, my son is doing the AoPS 6-8 th grade set (Algebra, Number Theory, Geometry, Counting & Probability, etc…).

Do you suggest we finish each chapter in AoPS and then, do yours?  I have heard lot of good things about your books.

Thank you and Best regards,

Y & S
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 March 06, 2013, 08:33:35 PM
from:    YMZ <[email protected]>
to:    [email protected]
date:    Wed, Mar 6, 2013 at 8:11 PM
subject:    Thank you

Dear Yongcheng,
 I want to thak you for your help. My son got state second place during the mathCount competition on Mar 2nd. He will go to Washington DC in May. I don't think he can get good position at national level competition this time because he did not do national competition practice.

If you have time, I want to get suggestion from you. What he should do next step? If he want to get progress at national competition level, what books he should read?
Thank you again for your help.


________________________________________________________________________________________

from:    yongcheng3315 <[email protected]>
to:    YZ <[email protected]>
date:    Wed, Mar 6, 2013 at 9:30 PM
subject:    Re: Thank you

Dear Dr. Zhang,

Thank you for letting me know this great news! Congratulations to your
child! He has two more years to go. Next year I am sure he will be
more than ready.

Next step will be practicing with all the national problems and AMC 10
problems.

We also have a sub forum we used to train national
competitors before, called national playfield. There are many good
mock tests at national levels.

Let me know your user name if you have one so I can add you to the group.

Thank you again for purchasing our books.

Good luck at National!

Yongcheng3315

: Re: 50 Matcounts lectures pdf files
: yongcheng3315 March 11, 2013, 07:14:56 AM
from:    BR <[email protected]>
to:    [email protected]
date:    Mon, Mar 11, 2013 at 1:33 AM
subject:    Thank you!

Hi, yongcheng3315:

My son took your MathCounts 50 lectures and AMC 50 lectures over the
last two summers, together with some other online and local classes,
and he has made significant improvements in his math skills. His AMC10
scores this year was improved by 18 points higher and during the past
weekend, he took the state MathCounts and made into our state team for
the national contest. We were very happy for his achievements and want
to thank you for your great training programs for us. Our state coach
had started the training with the four students for the national
contest, and I hope he will do well at the national level.

Regards

BR
__________________________________________________________

from:    yongcheng3315 <[email protected]>
to:    BR <[email protected]>
date:    Mon, Mar 11, 2013 at 9:10 AM


Thank you very much for letting me know this great news!

Big congratulations to your son and you!

I am so happy for your son and your family!

Good luck at national!!!!

Yongcheng3315
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 March 26, 2013, 08:55:13 AM
from:    DP <[email protected]>
to:    our mathcounts <[email protected]>
date:    Mon, Mar 25, 2013 at 9:01 AM
subject:    Update


Just an update.  We had our state math counts in Austin, and my son got x6 th place.  He is in 7 th grade..  He has one more year to give a good shot at it.  

To do that, I was wondering if you have any summer camp or equivalent for kids?  

Please let me know.  

Thanks

__________________________________________________________________________
from:    ourmathcounts <[email protected]>
to:    DP <[email protected]>
date:    Mon, Mar 25, 2013 at 6:55 PM
subject:    Re: Update

Thanks for letting me know.

Your child did a great job by ranking x6th in a big state that is very competitive as a 7th grader.

If he keeps working hard all the way through a whole year, I am sure he will improve a lot and have a great chance competing for the national team.

We are considering to do something in the coming summer and will let you know.

Thank s again for your trust and good luck to your son!

________________________________________________________________________
from:    DP <[email protected]>
to:    our mathcounts <[email protected]>
date:    Mon, Mar 25, 2013 at 8:03 PM
subject:    Re: Update

Thank you for the kind words. More importantly thank you for your support.

You would not believe how many times my son would look at your solution and say that is smart... You really have a neat way of dissecting the problem.

Kindly keep us in mind once you have formulated your plans for summer.

Thank you.
: Westminister Math Team use 50 lectures as study books
: yongcheng3315 July 16, 2013, 12:19:50 PM
Westminister Math Team use 50 lectures as study books

http://awinmath.blogspot.com/search?updated-max=2013-06-03T11:47:00-07:00&max-results=7
: Re: 50 Matcounts lectures pdf files
: yongcheng3315 January 25, 2018, 02:22:01 PM
回复:有人买过那个50 lectures for mathcounts 吗? 感觉怎样?
来源: 欢乐的爸爸 于 2014-02-26 12:42:49 [档案] [旧帖] [给我悄悄话] 本文已被阅读: 300 次 (464 bytes)
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回答: 有人买过那个50 lectures for mathcounts 吗? 感觉怎样? 由 tgifriday 于 2014-02-26 11:17:12

我家儿子的数学竞赛训练是从MC50讲开始的,之前只做Kumon。第一次接触MC50讲时有种惊为天书的感觉,原来竞赛训练还可以这样系统和深入,怪不得自己当年水平不高,没有这样的条件嘛。我们家用了两年的时间把MC50讲和AMC50讲都很仔细的攻下来了,受益非浅。现在回头看,觉得好的竞赛书其实有很多,不见得非选哪本书,重要的是学懂学透。我们在攻MC50讲时,着重的是学习作者的思想和技巧,至于发现书中的一些错误,倒觉得是自己的achievements,给永成发个mail 更正一下就是了,从没有什么反感的感觉 。

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