Twitter Math Puzzle and Solution
Yesterday I posted a very simple math puzzle to Twitter that I found in Jonathan Baron’s book, Thinking and Deciding. The puzzle is the following: Show that every number of the form ABC,ABC is divisible by 13. The puzzle comes up in Baron’s book as an example of an “insight problem” in which one goes [...]
The Price of Calculation
In a world in which the price of calculation continues to decrease rapidly, but the price of theorem proving continues to hold steady or increase, elementary economics indicates that we ought to spend a larger and larger fraction of our time on calculation.1 Over the next ten years, I hope that more and more mathematically [...]
Algebra and Education
Recently a friend asked me to help her learn enough math to take the GRE’s. My response was to give her the first problem that I thought she should be able to solve before we discussed anything else. It was a very simple problem from the perspective of a mathematician, but one that is not [...]