Start with a positive whole number n
Multiply n by every whole number below it down to 1
Write it as n! = n × (n – 1) × (n – 2) × … × 2 × 1
Example: 5! = 5 × 4 × 3 × 2 × 1
Calculate the product
Remember that 0! = 1
Use a calculator or recursion for large numbers