Question

How many four-digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 if the first digit cannot be 0? Repeated digits are allowed.

Answer 1

So first digit we have 9 choice
second digit 10
3rd 10
4th 10

9*10*10*10=9000

Answer 2

why is the 1st digit 9?

Answer 3

you have 9 choices 1 to 9

Answer 4

ohh okay and why are the 2ns 3rd and 4th numbers 10?

Answer 5

0- 9 ,----> 10 choices

Answer 6

The first digit can be any one of 9 digits since 0 can't be the first digit. The other 3 digits can be any one of 10 digits--0 through 9. Therefore, you get:

(9)(10^3)=(9)(1000)=9000

Answer 7

gotcha!!!! thank you!!!

Answer 8

You're welcome