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 all of the digits can be repeated?

The Options are:
A. 10 × 96
B. 9 × 107
C. 9 × 106
D. 107

Answer 1

I do believe c but idk

Answer 2

`9 \cdot 10^6`

Explanation:

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 all of the digits can be repeated

In 7 digit phone number, the first number cannot be 0

So only 1 to 9 are used to get the first digit. 9 numbers can be used

other digits can use number from 0 to 9. 10 number can be used

So possible numbers can be made is

`9 \ times \ 10 \ times \ 10 \ times \ 10 \ times \ 10 \ times \ 10 \ times \ 10`

`9 \cdot 10^6`