Factorial

What is factorial?
Product (multiplication) of all positive integers (including 0) less than or equal to n. In other words, multiply all numbers from to 1.

01
11
22 × 1 = 2
36
424
5120
6720
75040
840320
9362880
103628800

Examples:

  • = 4 × 3 × 2 × 1 = 24
  • 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040
  • 1
  • 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 3628800

10! = 10 × 9!, … and 125! = 125 × 124!, etc. How this can be described in a formula?

Where is just part of .

References