### Home > A2C > Chapter 10 > Lesson 10.2.5 > Problem 10-125

10-125.

Andrea has just purchased a five-digit combination lock. It allows her to set up her own combination. She can use the numbers 0 through 9 for her combination, and she must use five digits.

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

There are no repeats, but order does matter.

_{10}*P*_{5}= 30,240How many five-digit combinations are possible if she

*can*repeat the digits, but cannot use the same digit twice in a row?Now she has ten choices for each digit.