Combinations : Finding possible ways a social security number can be arranged.
1. A social security number has 9 digits. If numbers can be repeated and all numbers can be used, there would be 10^9 possible social security numbers. Find each of the following.
a. How many possible social security numbers are there if numbers can be repeated but 0 cannot be used for the first digit?
https://brainmass.com/math/combinatorics/combinationsfindingpossiblewaysasocialsecuritynumbercanbearranged18528
Solution Preview
0 can not be used for first digit, therefore, the number of ways by which the first digit can be formed by = 9 ways
Rest of the 8 digits can be formed by 10 ways.
Therefore, ...
Solution Summary
Combinations of digits in social security numbers are investigated.
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