Repeats allowedNo Repeats Permutations (order matters): nr n!(n − r)! Combinations (order doesn't matter): (r + n − 1)!r!(n − 1)! n!r!(n − r)!Mathopolis:Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Activity: Subsets Combinations and Permutations Calculator Pascal's Triangle ...