# Smooth number

A **smooth number** is an integer whose prime factors are less or equal to a prescribed bound (**smoothness bound**).

If this bound is B, we can say that the number is B-smooth.

For example the number 900 is 10-smooth, because

- 900 = 2
^{2}× 3^{2}× 5^{2}

Its greatest prime factor is 5, and 5 <= 10.