Combinations & Permutations Calculator
Compute nCr and nPr — with or without replacement. Choose order-matters or order-doesn't-matter.
When to use which?
- Combinations — order doesn't matter. Example: picking 3 toppings from 8 (a "sandwich combinations" problem).
- Permutations — order matters. Example: arranging 3 books from 10 on a shelf.
- With replacement — items can be reused. Example: rolling a 6-sided die 4 times → 6⁴ outcomes.