How it works
A walkthrough, end to end.
- 1
Enter a non-negative integer n.
- 2
The calculator returns n! as an exact integer plus the digit count.
- 3
BigInt is used so very large factorials don't overflow.
Reference
Factorial
n! = 1 × 2 × 3 × … × n. By convention, 0! = 1.
Use cases
What you can do with this.
Permutations and combinations
Building blocks for nPr and nCr.
Probability problems
Total arrangements of n objects.
Series & expansions
Taylor series use factorials in denominators.
Combinatorial counting
Counting all orderings of a set.
Discrete math homework
Quick exact answers for n! up to 1,000+.
Pi computation series
Many infinite series for π involve factorials.
Statistics check
Verify combinatorial counts in distributions.
Factorial 2026 — what's current
Standard combinatorial primitive.
FAQ
Frequently asked.
Capped at n = 5,000 for performance — that's already a 16,000-digit number.
1 by convention. The empty product is 1.
Not supported here. Use the gamma function for non-integers.
No. All math runs in your browser.