a symbol for a binary number is made up of these two bit symbols. the position of the bit symbols shows how big the number is. for example, the number 10 in the binary number system really means 1 times 2 plus 0, and 101 means 1 times four (=4) plus 0 times two (=0) plus 1 times 1 (=1). the binary number 10 is the same as the decimal number 2. the binary number 101 is the same as the decimal number 5.