### Home > CCA2 > Chapter Ch10 > Lesson 10.1.1 > Problem 10-21

10-21.

Andrea has just purchased a five-digit combination lock. It allows her to set up her own combination. She can use the numbers

How many five-digit combinations can she make so that no digit is repeated?

There are no repeats, but order does matter.

How many five-digit combinations are possible if she

*can*repeat the digits?Now she has ten choices for each digit.