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Factorial Calculator - n! Calculator

Free factorial calculator. Calculate n! (n factorial) for any positive integer. Used in permutations, combinations, and probability.

Calculate n! (n factorial)

Enter your values to see results

and click the "Calculate" button

What is Factorial?

Factorial (n!) is the product of all positive integers from 1 to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. By definition, 0! = 1.

n! = n × (n-1) × (n-2) × ... × 2 × 1

Common values: 0!=1, 1!=1, 5!=120, 10!=3,628,800

Why is 0! equal to 1?

By mathematical convention, 0! = 1. This makes formulas for permutations and combinations work correctly and maintains consistency in mathematics.

What is the largest factorial I can calculate?

Due to number size limitations, most calculators can handle up to 170! (about 7.26 × 10^306). Beyond this, the number is too large to represent.

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