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10-21.
  1. 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. For help with this problem, refer to the Math Notes box in this lesson. Homework Help ✎

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

    2. How many five-digit combinations are possible if she can repeat the digits?

There are no repeats, but order does matter.

10P5 = 30,240

Now she has ten choices for each digit.