Factorial n! of a positive integer n is defined as:
The special case 0! is defined to have value 0! = 1
There are several approximation formulae, for example, Stirling's approximation, which is defined as:
For simplicity, only main member is computed
with the claim that
This calculator computes factorial, then its approximation using Stirling's formula. Also it computes lower and upper bounds from inequality above.
For the UNLIMITED factorial, check out this unlimited factorial calculator