binary number system

System of numbers to base two, using combinations of the digits 1 and 0. Codes based on binary numbers are used to represent instructions and data in all modern digital computers, the values of the binary digits (contracted to ‘bits’) being stored or transmitted as, for example, open/closed switches, magnetized/unmagnetized disks and tapes, and high/low voltages in circuits.

The value of any position in a binary number increases by powers of 2 (doubles) with each move from right to left (1, 2, 4, 8, 16, and so on). For example, 1011 in the binary number system represents (1 × 8) + (0 × 4) + (1 × 2) + (1 × 1), which adds up to 11 in the decimal system.

The value of any position in a normal decimal, or base-10, number increases by powers of 10 with each move from right to left (1, 10, 100, 1,000, 10,000, and so on). For example, the decimal number 2,567 stands for (2 × 1,000) + (5 × 100) + (6 × 10) + (7 × 1).