Factorial Calculator

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

Shortcut to find trailing zeros in a factorial

Trailing zeros are a sequence of zeros in the decimal representation of a number, after which no other digits follow. This video shows how to find the trailing zeros of a factorial easily.

Factorial Calculator

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Sample Factorials Calculations.