Posted by **Jen** on Tuesday, July 26, 2011 at 5:08pm.

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?

- Math-New Questions -
**Count Iblis**, Tuesday, July 26, 2011 at 5:23pm
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

- Math-New Questions -
**Jen**, Tuesday, July 26, 2011 at 7:08pm
oooooh i totally got lost on this....

- Math-New Questions -
**Anonymous**, Tuesday, July 26, 2011 at 7:42pm
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 (=10^9-10^8)

- Math-New Questions -
**Jen**, Tuesday, July 26, 2011 at 8:41pm
SO ITS 1000000000-100000000 = 900000000??

- Math-New Questions -
**Anonymous**, Tuesday, July 26, 2011 at 9:39pm
yes

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