Counting principles and permutations. A social security number consists of 9 digits. How many different social security numbers are possible if repetition of digits is permitted. digits 0-9
I answered this question for you 20 minutes before you reposted it
http://www.jiskha.com/display.cgi?id=1363627561
What part of my answer did you not understand ?
it said 9 digits 0-9
Does this look right if it is 0-9
26*26*10*10*10*10=6,760,000
To find the total number of possible social security numbers with repetition permitted, we can determine the number of choices for each digit position and multiply them together.
Since each digit can be any number from 0 to 9, there are 10 choices for each digit position.
Since there are 9 digit positions in a social security number, we can apply the counting principle. According to the counting principle, the total number of possible social security numbers is obtained by multiplying the number of choices for each position together.
So, the total number of possible social security numbers is 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 = 10^9.
Therefore, there are 10^9 (1 billion) different social security numbers possible if repetition of digits is permitted.