Fun problem from China's hardest test

Описание: This question is from the notoriously difficult university entrance exam in China, the Gaokao exam.

2019 Gaokao test posts
https://www.sohu.com/a/319764212_9990...
https://www.zhihu.com/question/328262756
https://tomcircle.wordpress.com/2019/...
https://commons.wikimedia.org/wiki/Fi...
Jcw888us, CC BY-SA 4.0 via Wikimedia Commons

Members get early access to videos
YouTube members
   / @mindyourdecisions  
Patreon members
  / mindyourdecisions  

Support the channel with a one-time donation
https://www.paypal.com/donate/?hosted...

Subscribe: https://www.youtube.com/user/MindYour...

Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas!

If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.

Book ratings are from January 2025.

My Books (worldwide links)
https://mindyourdecisions.com/blog/my...

My Books (US links)
Mind Your Decisions: Five Book Compilation
https://amzn.to/2pbJ4wR
A collection of 5 books:
"The Joy of Game Theory" rated 4.2/5 stars on 564 reviews
http://amzn.to/1uQvA20
"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" rated 4.2/5 stars on 55 reviews
http://amzn.to/1o3FaAg
"40 Paradoxes in Logic, Probability, and Game Theory" rated 4.2/5 stars on 81 reviews
http://amzn.to/1LOCI4U
"The Best Mental Math Tricks" rated 4.3/5 stars on 148 reviews
http://amzn.to/18maAdo
"Multiply Numbers By Drawing Lines" rated 4.5/5 stars on 57 reviews
http://amzn.to/XRm7M4

Mind Your Puzzles: Collection Of Volumes 1 To 3
https://amzn.to/2mMdrJr
A collection of 3 books:
"Math Puzzles Volume 1" rated 4.4/5 stars on 138 reviews
http://amzn.to/1GhUUSH
"Math Puzzles Volume 2" rated 4.2/5 stars on 45 reviews
http://amzn.to/1NKbyCs
"Math Puzzles Volume 3" rated 4.3/5 stars on 38 reviews
http://amzn.to/1NKbGlp

2017 Shorty Awards Nominee. Mind Your Decisions was nominated in the STEM category (Science, Technology, Engineering, and Math) along with eventual winner Bill Nye; finalists Adam Savage, Dr. Sandra Lee, Simone Giertz, Tim Peake, Unbox Therapy; and other nominees Elon Musk, Gizmoslip, Hope Jahren, Life Noggin, and Nerdwriter.

My Blog
https://mindyourdecisions.com/blog/

Twitter
  / preshtalwalkar  

Instagram
  / preshtalwalkar  

Merch
https://teespring.com/stores/mind-you...

Patreon
  / mindyourdecisions  

Press
https://mindyourdecisions.com/blog/press