Permutations

How to use it

1. Total n = 8, selecting r = 3
2. Apply formule: P(8,3) = 8 × 7 × 6
3. Calculate: 8 × 7 = 56
4. Result: 56 × 6 = permutations

Common mistakes

• ⚠️ Using combinations formule instead of permutations
• ⚠️ Allowing r > n which gives invalid results
• ⚠️ Confusing when order matters vs doesn't matter

Worked example

Find the number of permutations when selecting items from distinct items.

The permutations {perm} count the number of ways to arrange r items from n when order matters.

Input guide