Question

A phone number contains 7 digits. How many different numbers can be made using the digits 0–9 if the first digit is not 0 and none of the digits can be repeated?

a. 362,880
b. 3,780
c. 24

Answer 1

beautiful combinations and permutations question

Answer 2

how does that work it's not one of my answers?

Answer 3

if the first digit is not zero, then that leaves 9 possible numbers

Answer 4

how do i calculate this?

Answer 5

therefore:

Answer 6

9 in the first combination

Answer 7

correctly permutation

Answer 8

giving 362, 880 posssibilities