Factorial Examples

3! = 3 × 2 × 1 = 6

4! = 4 × 3 × 2 × 1 = 24

6! = 6 × 5 × 4 × 3 × 2 × 1 = 720

Notice 6! = 6 × 5!. You can compute factorials recursively: n! = n × (n-1)!

For large n, use a calculator or code. 20! is already 2,432,902,008,176,640,000.