Posted by Jen on .
Social Security Numbers A social security number consists of nine digits. How many different social security numbers are possible if repetition of digits is permitted?
Is it 9^10?? 10 numbers correct?

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Count Iblis,
If you intepret the string of digits as numbers, then the numbers are between 10^8 and 10^9 1, so the answer is:
10^9  1  (10^8  1) =
10^9  10^8 
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Jen,
oooooh i totally got lost on this....

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Anonymous,
We can use the rule of product:
the first number we choose from 1 to 9,
the 2nd, 3rd,...,9th from 0 to 9.
So the number is
9*10*10*...*10=9*10^8 (=10^910^8) 
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Jen,
SO ITS 1000000000100000000 = 900000000??

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Anonymous,
yes