A caterpillar devouring books has raged in our encyclopedia. The 10 volumes of 500 pages each that make up the encyclopedia are arranged in order from left to right on a shelf, the caterpillar has begun to eat the first sheet of the first volume and has advanced in a straight line until devouring the last hour of the last book .
How many pages has the caterpillar eaten?
If the caterpillar travels in a straight line from the first page of the first volume to the last page of the last volume and the books are arranged as posed in the problem, in total it will have eaten 4002 pages, 4000 pages corresponding to the 8 central volumes plus the first page of the first volume and the last page of the last volume. If we also count the covers and back covers, it will have eaten 9 covers and 9 back covers.