Digit

A digit is a numeric symbol used to represent numbers in a positional numeral system. In the decimal system, digits are the ten symbols 0 through 9. More generally, a base-b numeral system uses exactly b distinct digit symbols, from 0 to b minus 1.

A number is written as a string of digits, where each digit's position indicates a multiple of the base power. For example, in decimal, the number 3,271 equals 3 × 10^3 + 2 × 10^2 + 7 × 10^1 + 1 × 10^0. Digits are typically arranged from most significant to least significant.

The term digit derives from the Latin digitus meaning finger or toe, reflecting historical counting on digits. In computing, a binary digit or bit is the most basic unit of data, taking values 0 or 1.

Digits can extend beyond 0–9 in higher bases; hexadecimal uses 0–9 and A–F to represent values 0–15. In typography, digits are often distinguished from letters and other symbols, and there are various styles of digits across typefaces.

See also Numeral, place value, numeral system, base, binary.