Skip to main content
Back to Numbers generators

Numbers

Factorial Generator

Used by developers, writers, and creators worldwide.

A factorial generator computes the exact factorial of a whole number — written n! — which is the product of every whole number from 1 up to n. So 5! = 5 × 4 × 3 × 2 × 1 = 120. Enter a value and it returns the precise result using big-integer arithmetic, so even large factorials are exact rather than rounded. Students use it to check homework and see how explosively factorials grow, while anyone working with combinatorics uses it to compute the building blocks of permutations and combinations. Factorials grow staggeringly fast — 20! already exceeds two quintillion — which makes them impossible to work out by hand past small values. For very large inputs the result is shown with its digit count, so you can see just how immense these numbers become. Use it to verify a calculation or teach the concept.

Loading usage…

Free forever — no account required

How to use

  1. Choose your options above
  2. Click Generate
  3. Copy your result

Detailed instructions

  1. Enter a non-negative whole number.
  2. Click Generate to compute its factorial.
  3. Read the exact result, with a digit count for large values.
  4. Use it to check homework or feed combinatorics formulas.

Use Cases

  • •Checking factorial homework answers exactly
  • •Computing building blocks for permutations and combinations
  • •Exploring how fast factorials grow
  • •Teaching the factorial concept with real values
  • •Getting an exact large factorial without rounding

Tips

  • →Remember 0! equals 1 by definition.
  • →Factorials grow explosively — 20! already exceeds 2 quintillion.
  • →Use exact factorials when computing nCr and nPr.
  • →The digit count shows just how large big factorials get.

FAQ

what is a factorial

The factorial of n, written n!, is the product of all whole numbers from 1 to n. For example 4! = 4 × 3 × 2 × 1 = 24. By definition 0! = 1. Factorials count the ways to arrange n distinct items in order.

are the results exact for large numbers

Yes. The tool uses big-integer arithmetic, so even large factorials are computed exactly to the final digit rather than rounded to a floating-point approximation. For big results it also shows the digit count.

why is there an upper limit

Factorials grow so fast that the result quickly becomes thousands of digits long. The cap keeps the output displayable and the page responsive while still covering far more than any practical hand calculation.