Question

What is a factorial number?

Answer 1

the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, The value of 0! is 1, according to the convention for an empty product.

Answer 2

Factorials are very simple things. They're just products, indicated by an exclamation mark. For instance, "four
factorial " is written as "4!" and means 1×2×3×4 = 24. In general, n! ("enn
factorial ") means the product of all the whole numbers from 1 to n; that is, n! = 1×2×3×...×n.