A typical Social Security identification number is 805-83-3253. How many Social Security numbers are possible if the first digit of each group cannot be 0?
A) $1,000,000,000$
B) $387,420,489$
C) $1,000,000$
D) $729,000,000$
E) $4,782,969$

Question

Quizplus · Accepted Answer

The first digit cannot be zero, so there are only nine possibilities (1-9) for the first digit of each group. Therefore, the total number of Social Security numbers possible is:
$9\cdot10\cdot10\cdot10\cdot10\cdot10\cdot10\cdot10\cdot10 = 9	imes10^8 = 729,000,000$
So, the answer is $(D)$.

A Typical Social Security Identification Number Is 805-83-3253 1,000,000,0001,000,000,0001,000,000,000 B) 387,420,489387,420,489387,420,489 C) 1,000,0001,000,0001,000,000

A Typical Social Security Identification Number Is 805-83-3253 $1,000,000,000$ B) $387,420,489$ C) $1,000,000$