I needed to calculate the factorial of 5 for a math problem.

There is a New Year's celebration in January.

He always likes to be the first to comment on videos.

The tip of this pen is only 1 millimeter.

In this experiment, we will use the International System of Units.

An identity matrix is a square matrix in which all the elements on the diagonal are 1 and all other elements are 0.

An imaginary unit is an important concept in mathematics.

An astronomical unit represents the average distance from the Earth to the Sun.

This product has a very small assembly unit.

This room is 20 square meters.