- A representation of a fraction or other real number using the base ten and consisting of any of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and a decimal point. Each digit to the left of the decimal point indicates a multiple of a positive power of ten, while each digit to the right indicates a multiple of a negative power of ten. For example, the number 2637100 can be written in decimal notation as 26.37, where 2 represents 2 X 10, 6 represents 6 X 1, 3 represents 3 X 110 or 310, and 7 represents 7 X 1100 or 7100.