In algebra, you use permutations to count the number of subsets of a larger set. Use permutations when order is necessary. With combinations, you can count the number of subsets when order doesn't matter. The formulas you need are

In algebra, you use permutations to count the number of subsets of a larger set. Use permutations when order is necessary. With combinations, you can count the number of subsets when order doesn't matter. The formulas you need are
Mary Jane Sterling is the author of numerous For Dummies books. She has been teaching at Bradley University in Peoria, Illinois, for more than 25 years.