Question

A social security number contains nine digits, such as 833-49-4271. How many different socialsecurity numbers can be formed?

Answer 1

here the digit is a security number is 9

so we have 9 places here,

a single place can contain digit 0 to 9

so total 10 digit is possible at one place,

for the 9 places, the possible numbers can be

$10^9$

so the answer is 10^9

$10^9\text{ different social security numbers can be formed.}$