Calculate the Factorial

How to use Calculate the Factorial

1. 1. Paste your numbers. Enter one or more non-negative integers, one per line or separated by commas. Each number's factorial is computed independently.
2. 2. Read the factorial results. The tool multiplies each number by every positive integer below it, so 5! becomes 5 x 4 x 3 x 2 x 1, and handles large factorials without overflow.
3. 3. Copy the results. Copy the factorial values from the output and use them in your permutation calculation, probability problem or programming reference.

When to use Calculate the Factorial

Calculate the Factorial multiplies a number by every positive integer below it, the operation behind permutations, combinations and many probability formulas. It handles large inputs correctly instead of overflowing like a standard calculator app.

• Computing permutations for a probability problem. A statistics assignment asks how many ways a set of items can be arranged, and you need the factorial of the item count to plug into the permutation formula.
• Verifying a combinations calculation. Before computing n choose k for a lottery or card-game probability question, you need the factorials of n, k and n minus k to plug into the formula.
• Testing a factorial function for overflow. A developer writing a factorial function in a language with fixed-size integers wants to see the correct large-number result to know at what input their code starts to overflow.
• Checking a math competition answer. A competition problem involves a factorial of a moderately large number, and you want to confirm your manual multiplication before submitting the final answer.

Examples

5
10

5! = 120
10! = 3628800

About the Calculate the Factorial tool

Frequently asked questions