Given:
A social security number contains nine digits.
As there are 10 digits from 0 to 9.
There are 9 positions and every position has 10 possibilities.
If repetition is allowed the number of ways are,
[tex]\begin{gathered} \text{Number of ways=10}\times10\times10\times10\times10\times10\times10\times10\times10 \\ =10^9 \\ =1000000000 \end{gathered}[/tex]
Answer: the number of ways are,
[tex]1000000000[/tex]
