Question 28323: A telephone number consist of seven digits, the first three representing the exchange. How many different telephone numbers are possible within the 537 exhange?
Answer by josmiceli(19441)   (Show Source):
You can put this solution on YOUR website! Subtract 3 from 7, because the exchange is always the same. That leaves 4 digits
the number of possible digits is 10 namely, 0,1,2,3,4,5,6,7,8,9
Each of these 10 possible digits can combine with the second digit's 10 possibilities in 10 x 10 different ways. These 10 x 10 possibilities can
combine with the third digit in 10 x 10 x 10 different ways.
These 10 x 10 x 10 possibilities can
combine with the fourth digit in 10 x 10 x 10 x 10 different ways.
So the answer is 
|
|
|
