Numbers index

  10001001   Binary   10010001  

Binary numbers --- Introduction --- Addition --- Multiplication --- Counter --- Card game

Since we learn about numbers when we're young, it's easy to think that this is the only way to count and do arithmetic. But it isn't. We count in Arabic numbers, which are base 10 or decimal, probably because we have ten fingers. You count from 1 to 10 using your fingers, and then use someone else's fingers to keep count of how many tens you have counted so far. That takes you up to a hundred, and then you need a third person to keep track of the hundreds. However, computers only need two digits, 0 and 1. Perhaps they only have two fingers! They do their arithmetic using Base 2 or binary.

Binary has been known in many forms for a long time, but the modern system was documented by Leibniz in the 17th century. He used the symbols 0 and 1. Binary is used today by computers. It is a positional system, like Arabic numbers.