Comprehensive Calculator Guide
This calculator works out n!, the product of the whole numbers from 1 to n, for any n up to 1,000: exact up to 25! and in scientific notation beyond, with its digit count and trailing zeros. 5! = 120, 10! = 3,628,800, and 100! has 158 digits ending in 24 zeros.
Factorials
n! = n × (n − 1) × … × 1, and 0! = 1. It counts the ways to arrange n different things. Trailing zeros come from factors of 5: 100! has ⌊100/5⌋ + ⌊100/25⌋ = 24.
How to Use
- Enter a whole number from 0 to 1,000.
- Nothing else is needed.
- Press “Calculate” to see n!, its digits and trailing zeros.
Formula Used
n! = n × (n − 1) × … × 1, 0! = 1
Practical Examples
- Example 1: 5!
- 120.
- Example 2: 10!
- 3,628,800.
- Example 3: 100!
- About 9.332621 × 10¹⁵⁷, 158 digits.
Important Tips
- Cancel before multiplying: 10!/8! = 90.
- Use factorials for arrangements.
- For big n, the digit count is often enough.
Common Mistakes to Avoid
- Taking 0! as 0.
- Dividing 10 by 8 for 10!/8!.
- Counting zeros by dividing by 10.
Frequently Asked Questions
- Why is 0! = 1?
- There is one way to arrange nothing.
- What is 10!?
- 3,628,800.
- How many zeros end 100!?
- 24.