2019 AIME I reflection notes from H

2019 AIME I — Reflection Notes from H

9 out of 15, 2 didn't finished were very close. like to know if there is better strategies for some problems.

Quick stats
• #1–5 took about 22.5 min total.
• #6 took about ~20 min (time sink).

My answers (as written)
#1: 342
#2: 029
#3: 120
#4: 122
#5: 252
#6: 090
#7: 880
#8: (very close — not finished)
#9: (wrong / crossed out)
#10: 357 (marked “silly”)
#11: ✓ (got it, but messy)
#12: (very close — basically solved but error)
#13: (basically solved, but used the wrong operation / wrong term; didn’t finish)
#14: 097
#15: (did not attempt)

Had trouble / wrong

#6 – Tried using binomial expansion, but it became too much computation (huge time sink).
#9 – Went nowhere / ended up crossing it out.
#10 – Silly mistake (need to slow down + verify).
#13 – Basically solved, but multiplied/used the wrong thing (wrong term like a_i) and didn’t finish.

Very close / almost

#8 – Very close (need to push to the finish next time).
#12 – Basically solved, but made an operation mistake (multiplied when I shouldn’t / wrong step).

Need review / improve

#11 – Got it, but I couldn’t visualize well, and the computations got messy.
#14 – Some algebra at the end felt annoying; practice finishing cleanly under time.

Not attempted

#15 – Did not attempt.

2025/2026 Mathcounts, AMCs, AIMEs Competition Preparation Strategies

Hi, Thanks for visiting my blog.

E-mail me at thelinscorner@gmail.com if you want to learn with me.  :) :) :) 

Currently I'm running different levels of problem solving lessons, and it's lots of fun learning along with students from different states/countries. 

So many students are not learning smart.

Problem solving is really fun (and a lot of the times very hard, yes).

Good questions are intriguing and delicious, so come join our vibrant community and have the pleasure of finding things out on your own.

5 ways to kill your dreams from TED Talk

There is no overnight success.

Testimonials from my students/parents.   :) 

My other blogs :

thelinscorner  : Standardized test preps (ONLY the hardest problems), books, links/videos for life-time learning

Studentsspeak Magazine  (featuring students' independent projects)

Take care and have fun learning.

Don't forget other equally interesting activities/contests, which engage your creativity  and imagination. 
Some also require team work. Go for those and have fun !! 

Don't just do math.  

11 Qualities Google Looks For In Job Candidates 

In Chinese : 《專題報導》亞裔尖子生 職場難出頭？

Before going full throttle mode for competition math, please spend some time reading this
well- thought-out article from BOGTRO at AoPS "Learn How to Learn".

It will save you tons of time and numerous, unnecessary hours without a clear goal, better method in mind.

Less is more. My best students make steady, very satisfactory progress in much less time than those
counterparts who spent double, triple, or even more multiple times of prep with little to show.

It's all about "deliberate practices", "tenacity", and most of all, "the pleasure of finding things out on your own".

Take care and have fun problem solving.

I have been coaching students for many years. By now, I know to achieve stellar performance you need :
Grit (from TED talk), not only that but self-awareness (so you can fairly evaluate your own progress) and a nurturing-caring environment. (Parents need to be engaged as well.)
               
Thanks a lot !!  Mrs. Lin

"Work Smart !!" , "Deliberate practices that target your weakness ", " Relax and get fully rested.", "Pace your time well", "Every point is the same so let go of some questions first; you can always go back to them if time permits."

"It's tremendous efforts preparing for a major event on top of mounting homework and if you are the ones who want to try that, not your parents and you work diligently towards your goal, good for you !!"

"Have fun, Mathcounts changes lives, because at middle school level at least, it's one of those rare occasions that the challenges are hard, especially at the state and national level."

Now, here are the links to get you started: 

Of course use my blog.  Whenever I have time I analyze students' errors and try to find better ways (the most elegant solutions or the Harvey method I hope) to tackle a problem. Use the search button to help you target your weakness area.

Newest Mathcounts' competition problems and answer key

For state/national prep, find your weakness and work on the problems backwards, from the hardest to the easiest. 

Here are some other links/sites that are the best.

Mathcounts Mini : At the very least, finish watching and understanding most of the questions from 2010 till now and work on the follow-up sheets, since detailed solutions are provided along with some more challenging problems.

For those who are aiming for the state/national competition, you can skip the warm-up and go directly to "The Problems" used on the video as well as work on the harder problems afterward.

Art of Problem Solving 

The best place to ask for help on challenging math problems. 

Some of the best students/coaches/teachers are there to help you better your problem solving skills.

                                                             Do Not Rush !!

Awesome site!!
       
For concepts reviewing, try the following three links.
 
Mathcounts Toolbox
 
Coach Monks's Mathcounts Playbook
 
You really need to understand how each concept works for the review sheets to be useful.

To my exasperation, I have kids who mix up the formulas without gaining a true understanding and appreciation of how an elegant, seemingly simple formula can answer myriads of questions.

You don't need a lot of formulas, handbook questions, or test questions to excel.

You simply need to know how the concepts work and apply that knowledge to different problems/situations.

Hope this is helpful!!

2018 AIME I reflection notes from H

2018 AIME I — Reflection Notes from H

Had trouble / wrong: #9, #10, #12, #13

Need Review / Unclear:

#9 – I got the first two terms of the final sum, but I didn’t understand / account for the double counting. a + b = 16 abd b + c = 24.

#10 – Did casework and isolated the 3’s, but wasn’t able to finish.

#12 – I got ±5 (and split into ~15 cases), but couldn’t compute after that.

#13 – Very close, but couldn’t simplify the trig at the end in the expression for the area.

2017 AIME II reflection notes from H

AIME 2017 II — Reflection Notes from H

Correct: #8, #10, #11, #12, #13

Had trouble / wrong: #9, #14, #15

Need Review / Unclear:

#9 – The “given that” statement kind of confused me. I wasn’t sure how to use it / what it was trying to tell me, so I got stuck early.

#14 – No idea how to start. I couldn’t visualize the setup, so I didn’t know what to do next.

#15 – Tried using generating functions, but it became too complicated (too many moving parts). Need a cleaner setup / approach.

2017 AIME I reflection notes from H

Correct: #8, #9, #11, #12, #14

Had trouble / wrong: #10, #13, #15

Need Review / Unclear:

#10 – Tried looking at this geometrically, but couldn’t find the right cyclic quadrilateral / setup (kept thinking about points like z₁, z₂, z₃, etc.). Need to learn how to “see” the key circle configuration faster.

#13 – I knew Q(m) would eventually become 1, but I didn’t realize it would happen at such a small value of m. This could have been done with quicker mental casework / checking small m first.

#15 – Tried using trig, but it got very complicated (too many variables). Need to practice spotting a cleaner non-trig / inequality setup sooner.