CK-12 Foundation
Ck 12: Permutations and Combinations Compared Grades 9 10
[Free Registration/Login may be required to access all resource tools.] Given a set, learn how to calculate its number of permutations.
CK-12 Foundation
Ck 12: Probability: Permutations and Combinations Compared
[Free Registration/Login may be required to access all resource tools.] Covers the formula for permutations.