Question 1

When should I use combinations vs permutations?

Accepted Answer

Use combinations when order does not matter (selecting a group). Use permutations when order matters (arranging or ranking).

Question 2

What if r equals n?

Accepted Answer

For combinations, nCn equals 1. For permutations, nPn equals n! since all items are arranged.

Question 3

Why do factorials get large quickly?

Accepted Answer

Factorials grow super fast. Big-number support or logarithmic math can help keep calculations feasible.

Permutation & Combination Calculator

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