Question 76086: A telephone number consist of seven digits the first three representing the exchange. How many different telephone numbers are possible with in the 537 exchange? Answer by Cintchr(481) (Show Source):
You can put this solution on YOUR website! The last 4 digits determine how many numbers there are in the exchange.
Because this involves INCLUSIVE numbers, we subtract the first number from the last and then ADD 1. The reason we add one is that we have in INCLUDE the fisrt one.
So you can see that this really works, lets look at a simpler problem:
You are supposed to read pages 1 - 5 in your history book. How many pages dod you read?
A total of 5