反はん数すう

noun

additive inverse; opposite number

In mathematics, the number that when added to a given number yields zero. For example, the additive inverse of 5 is -5.

• 5の反はん数すうは-5です。

  The additive inverse of 5 is -5.

noun

reciprocal number

Rare mathematical term for the reciprocal (逆数). Cross-referenced with 逆数, which is the standard modern term. This usage is uncommon and may be considered outdated or nonstandard.

See also: 逆数 (ぎゃくすう)

• 古ふるい数すう学がく書しょでは、逆ぎゃく数すうの意い味みで「反はん数すう」が使つかわれることがある。

  In old mathematics books, 反数 is sometimes used to mean the reciprocal.