Reciprocal altruisms are important for maintaining social bonds.

Reciprocating engines are commonly used in small aircraft.

They helped each other with their homework.

I used a reciprocating saw to cut through the metal pipe.

Reciprocating saws are commonly used in construction projects.

The reciprocal proportion between x and y is evident in their relationship.

A prime reciprocal magic square is a square grid of numbers where the sum of each row, column, and diagonal is the same and the reciprocals of the numbers are also prime.

Prime reciprocal magic squares are a fascinating mathematical concept.