Here is the answer to questions like: What is the factorial of 20? What is the last digits of factorial of 20? How many trailing zeros in 20 factorial? How many digits are there in 20 factorial? Use the factorial calculator below to find the factorial of any real number between 0 and 10.000.
What is factorial?
Definition of factorial
The factorial is a quantity defined any all integer x greater than or equal to 0.
The factorial is the product of all integers less than or equal to x but greater than or equal to 1. The factorial value of 0 is by definition equal to 1. For negative integers, factorials are not defined. The factorial can be seen as the result of multiplying a sequence of descending natural numbers (such as 3 × 2 × 1). The factorial symbol is the exclamation mark !.
The factorial formula
If n is an natural number greater than or equal to 1, then
n! = n x (n - 1) x (n - 2) x (n - 3) ... 3 x 2 x 1
If p = 0, then p! = 1 by convention.
Example: 6! = 6 x 5 x 4 x 3 x 2 x 1 = 720
Table of Factorials until 30
Sample Factorials Calculations.