In mathematics, a perfect number refers to a number where the sum of its divisors, excluding the number itself, equals the number.

This fish is completely farmed, and no capture is done in the natural environment.

He is immersed in the study of panmagic squares.

A terrestrial planet may have an environment similar to Earth.

A Jovian planet is similar to Jupiter in terms of its size and composition.

He is a perfectionist, so he is very strict about his work.

He played a perfect fifth scale on the piano.