Enter values and select Calculate.
Calculated result
Formula and worked example
n! = n × (n − 1) × … × 2 × 1 for n ≥ 1, with the defined base case 0! = 1.
5! = 120, 10! = 3,628,800, and 20! = 2,432,902,008,176,640,000.
Input and exactness policy
Only nonnegative integers are accepted; decimals and negative values are rejected.
The maximum is 5,000 to keep browser work and output size bounded.
Every successful factorial result is retained and copied as an exact integer.
Large output handling
Long integers wrap within the result panel instead of creating page-level horizontal scrolling.
A digit count accompanies the exact value for orientation.
Scientific notation is not substituted for the exact result.
Factorial boundaries
This page implements ordinary n! only.
Gamma and generalized factorials are outside the accepted input domain.
Permutation and combination calculators remain possible future products and are not created here.
Methodology and limits
This deterministic browser-local tool uses strict complete-value parsing and the displayed mathematical definition. It does not evaluate expressions, execute entered text, call a remote service, or silently cross its documented real-number or integer domain.