# 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!