Telephone numbers consist of seven digits; the first digit cannot be 0 or 1. How many telephone numbers are possible?

Question

Telephone numbers consist of seven digits; the first digit
cannot be 0 or 1. How many telephone numbers are
possible?

Answer 1

0,1,2,3,4,5,6,7,8,9

10 digits in all

the first digit can be chosen from only 8 digits (no 0 or 1)

the other digits can each be chosen from the 10 digits; there was no mention of "no repetition" so digits can be repeated

8*10*10*10*10*10*10=8,000,000