Factorial Calculator
Find n! with the full multiplication expanded.
What is a factorial calculator?
A factorial calculator finds n!, the product of all whole numbers from 1 up to n. Factorials are used in counting, probability and combinations.
How to use the factorial calculator
Enter a whole number and click Calculate. The calculator shows the factorial with the full multiplication expanded.
Factorial formula
n! = n × (n − 1) × (n − 2) × … × 2 × 1. By definition, 0! = 1.
Example
5! = 5 × 4 × 3 × 2 × 1 = 120. And 0! = 1.
Frequently Asked Questions
What is 5!?
5! = 120. Try it on the calculator above.
What is 0!?
0! = 1 by definition. Try it on the calculator above.
Why are factorials useful?
Factorials count how many ways things can be arranged. For example, 5 books can be arranged in 5! = 120 ways.
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