Fatorial

How to use it

1. Calculate 7!
2. Multiply: 7 × 6 × 5 × 4 × 3 × 2 × 1
3. Step by step: 7×6=42, 42×5=210, 210×4=840
4. Continue: 840×3=2520, 2520×2=5040, 5040×1=5040

Common mistakes

• ⚠️ Forgetting that 0! = 1 by definition
• ⚠️ Trying to calculate factorial of negative numbers
• ⚠️ Integer overflow for large n values (>170)

Worked example

Calculate the factorial of 7.

The factorial {fact} is the product of all positive integers from 1 to n.

Input guide