A Social Security number has nine digits How many Social Sec

A Social Security number has nine digits. How many Social Security numbers are possible?

since there are 9 digits and each digit has 10 options (i.e. 0,1,2,3,4,5,6,7,8,9) that means you multiply the number of options for each digit 9 times: 10x10x10x10x10x10x10x10x10 or 10^9 which equals 1,000,000,000 (1 billion)