Factorial Calculator
Last updated: July 2026
Calculate n factorial, its digit count, trailing zeros and a simple permutation count.
n factorial
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- Number of digits: —
- Trailing zeros: —
- n permutations taken 2 at a time: —
On this page
Quick summary: Calculate n factorial, its digit count, trailing zeros and a simple permutation count. Enter the requested values, calculate, review the result, and compare more than one realistic scenario before making a decision.
Read the complete guide
What this calculator estimates
Calculate n factorial, its digit count, trailing zeros and a simple permutation count. It is designed for fast planning and comparison in the United States. The output is an estimate, not a binding quote, approval, tax determination, insurance offer, legal conclusion, medical recommendation or professional advice.
How to use it
Enter the requested values using a single consistent time period and currency. Select Calculate, review the headline result and supporting figures, then change one assumption at a time to compare another scenario.
How the calculation works
Factorial multiplies every positive whole number from one through n. Trailing zeros are counted from factors of five.
Important limitations
The calculator accepts whole numbers from zero through 170 to keep output and browser performance manageable.
Frequently asked questions
Is the result exact?
No. It is a planning estimate based on the assumptions entered.
Can I compare different scenarios?
Yes. Change one input at a time so you can see which assumption changes the result.
Does the calculator store my inputs?
The calculation runs in the browser and does not require an account. Avoid entering unnecessary confidential information.