If the lead digit can be a zero
then 10^9
If the lead digit cannot be a zero
then 9(10^8)
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
2 answers
If the lead digit can be a zero
then 10^9
If the lead digit cannot be a zero
then 9(10^8)
then 10^9
If the lead digit cannot be a zero
then 9(10^8)