Looking onto a shelf you see three books each labeled Volume 1, Volume 2, and Volume 3 respectively.
Each book is 2.5 inches thick; that is the pages are 2 inches, and each cover .25 inches.
A bookworm begins eating it’s way from the first page of Volume 1, and stops at the last page of Volume 3.
How many inches did the bookworm travel? (Note he goes in a straight line and can eat through covers, if need be)
The key here is to understand that when a book is on a shelf, the first page is furthest to the right, as the last is to the left. After that knowledge, it’s simple math.