Question

Area codes are made up of three digit numbers
a. If all numbers can be used for each digit, how many area codes are possible
b. How many area codes would be possible if repetition is not allowed?

Answer 1

For option a:
Since all 10 digits may be used for the code, the total number of possibilities would simply be the product of 10, 9 and 8.

Answer 2

sorry that's for option b

Answer 3

Did you understand how its 10 X 9 X 8?

Answer 4

yes

Answer 5

For option a since you can have repetition, you can use the same digit thrice. So it would be 10 x 10 x 10.

Answer 6

1,000