June 2001

Counting to 31 on One Hand and 1023 on Two Hands

Check this out. We all know how to count to ten on our fingers. Well guess what? You can actually count to 31 on one hand and a whopping 1023 on two hands. It's easy. Your fingers represents digit positions in a binary number. That means that with a given number of fingers, X, you can count to 2^X - 1 (where '^' means 'to the power of'). On one hand, there are five fingers, so this is 2^5 - 1, which equals thirty-one. Here are the hand representations for each of the thirty-two numbers in the range zero through thirty-one (right hand palm up or left hand palm down, it doesn't really matter):