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| Math Central | Quandaries & Queries |
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Question from Michael: We have a 3 digit lock that only allows for 5 possible numbers to be used. (The numbers can repeat) What are the total number of combinations that can be created. |
Hi Michael,
Think about randomly guessing the combination. For the first digit you have 5 choices and regardless of your choice you have 5 choices for the second digit. Thus you have 5 × 5 = 55 = 25 choices for the first two digits.
Finally, whatever choices you have made for the first two digits you have 5 choices for the third digit. Thus in total you have 5 × 5 × 5 = 53 = 125 possible combinations.
Penny
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