Normally you count with your fingers by stretching them out one after another. You don't care about which ones are stretched out, but only about the amount of them. Each of them is as significant as the other. By changing the significance in the way that the right thumb has significance 1 and the left neighbor neighbor is always twice as significant we can get 1024 different numbers. 1+2+4+8+16+32+64+128+256+512=1023 and 0. This is called binary counting and exactly the way a computer counts but with zeros and ones instead of bent and stretched fingers.