Factorial

The concept of factorial numbers is widely used in combinatorics.

So what is factorial? Suppose we want to calculate the factorial of the number 9. To do this, multiply all the numbers from 1 to 9.

1⋅2⋅3⋅4⋅5⋅6⋅7⋅8⋅9=362 880

This is the factorial. Thus, to find the factorial of any number, you need to multiply all numbers from 1 to this number.