Numeral system
Various symbols are used as numerals to make numbers. A system with base 10 (the common decimal system), normally uses the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Each of the numbers 0 to 9 can be written as one symbol, 0 ... 9. To count past 9, symbols have to be put together. 10 can be seen as 1 in the tens' place and 0 in the ones' place, or as 1 times 101 plus 0 times 100. With a base of 2, only the symbols 0 and 1 are used. 10base 2  is therefore 1 times 21 plus 0 times 20. This is the same as 2, in the base 10 notation.