Reciprocal
From ACT Wiki
1. Maths.
The reciprocal of a number is 1 divided by that number.
For example, the reciprocal of 0.05 (5%) is 1 / 0.05 = 20.
2.
Reciprocal also refers to something done in return for the granting of a favourable treatment or other advantage, especially when the thing done in return is perceived as being of equal value, or symmetrical.