noun
reciprocal; multiplicative inverse
Mathematical term for the number which, when multiplied by the original number, yields 1. Used in arithmetic and algebra.
二の逆数は二分の一です。
The reciprocal of 2 is one half.
分数の割り算では、割る数の逆数を掛けます。
In division of fractions, you multiply by the reciprocal of the divisor.