Question

SOCIAL SECURITY Social Security numbers are of the form XYZ - MN - ABCD. A. The first three digits XYZ are referred to as the area number. The number is associated with where you registered for your social security card. X is a number 1-7. Y and Z can be any number 0-9. Also the area code 666 has never been used. How many area code numbers are possible? 10SHOW YOUR WORK

Answer 1

Social Security numbers are of the form XYZ - MN - ABCD

Part A:

The first three digits XYZ are referred to as the area number

X is a number 1 - 7 (1, 2, 3, 4, 5, 6, 7)

That means we have 7 choices for X

Y and Z can be any number 0 - 9 (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

That means we have 10 choices for Y and also 10 choices for Z

So, the number of possible ways are

$7\times10\times10=700$

But we know that the area code 666 has never been used.

So we need to subtract this one from the total.

$700-1=699$

Therefore, the total number of possible area codes is 699.