Asked by slomomo

Counting Principles and Permutation. A social security number consists of 9 digits. How many different social security numbers are possible if repetition of digits is permitted
Answered by Reiny
If the lead digit can be a zero
then 10^9
If the lead digit cannot be a zero
then 9(10^8)
Answered by Reiny
If the lead digit can be a zero
then 10^9
If the lead digit cannot be a zero
then 9(10^8)
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