A Pythagorean Number Puzzler

Here’s a classic puzzle:

Write the numbers 1 through 100 on a board. Pick two numbers a and b at random, erase them and replace them with the single number a+b+ab (the sum of their sum and their product). Do this 99 times until there is a single number on the board. Which number MUST that single number be?

This video is not that puzzle!

A Pythagorean Number Puzzler

• ON-LINE SHORT COURSES!

  QUADRATICS, Permutations and Combinations, EXPLODING DOTS, and more!

  Written for educators - and their students too! - this website, slowly growing, takes all the content Tanton has developed in his books, videos, and workshops, and organizes it into short, self-contained, and complete, curriculum units proving that mathematics, at all points of the school curriculum, can be joyous, fresh, innovative, rich, deep-thinking, and devoid of any rote doing! Let's teach generations of students to be self-reliant thinkers, willing to flail and to use their common sense to "nut their way" through challenges, to assess and judge results, and to adjust actions to find success. (Great life skills!)

  CHECK OUT: www.gdaymath.com

• Books

  • Thinking Mathematics! (TEN VOLUMES)
  • Solve This: Mathematical Activities for Students and Clubs
  • Encyclopedia of Mathematics
  • Geometry I & II

• Get in touch

  Email: tanton.math@gmail.com