Factorial Calculator | Calculate n! Step-by-Step | PanMaths
Fast and accurate factorial calculator. Just enter a number n to find n! (the product of all integers from 1 to n).
⚡ Popular Factorial Presets:
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Factorial Formula
n! = n × (n-1) × (n-2) × ... × 1Multiplying a sequence of descending natural numbers.
Special Case
0! = 1By definition, the factorial of zero is one.
Examples
Finding 4!
4! = 4 × 3 × 2 × 1 = 24
Finding 6!
6! = 6 × 5 × 4 × 3 × 2 × 1 = 720
Frequently Asked Questions
Why is 0! equal to 1?
There is exactly one way to arrange zero items (the empty set), so 0! = 1. This also makes many mathematical formulas (like combinations) work consistently.
Can factorials be negative?
Standard factorials are defined only for non-negative integers. For negative numbers and fractions, mathematicians use the Gamma Function.