# ones' complement

## English

### Noun

ones' complement (plural ones' complements)

1. (computing) The number obtained by subtracting a given n-digit binary number from $2^n - 1$ (which yields the same result as the logical complement).
The ones' complement of 0xAAAA is 0x5555 on a 16-bit machine, and 0xFFFF5555 on a 32-bit machine.
2. (computing) The convention by which bit patterns with high bit 0 represent positive numbers from 0 to $2^{n-1} - 1$ directly, while bit patterns with high bit 1 represent negative numbers from 0 to $-(2^{n-1} - 1)$, n being the word size of the machine, and the numeric complement of a number is its ones' complement.
Computers that use ones' complement arithmetic have two representations for zero, all 0's and all 1's.

#### Translations

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