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Doing the Math

I love the problem as it shows the importance of drawing it out, or pulling out books to make sense of the problem. It is easy to forget how books actually sit on the shelf.

Okay - I'm going to take a risk and give this a shot!


Book 1 front cover + Book 2 back cover + Book 2 pages + Book 2 front cover + Book 3 back cover


1/8" + 1/8" + 2" + 1/8" + 1/8" = 2 1/2" The bookwork ate through 2.5 inches of book.


I had to draw this one out in order to make sense of the context. I drew three separate vertical rectangles to represent the books. This way I could also see and make sense of the book covers and the orientation of the books on the shelf with their spines out.


This is a great riddle to show the connection between context, representations and understanding!

This year, the idea of doing the math has surfaced multiple times. There is one problem that stands out.

I have 3 books on a bookshelf, and they are part of a 3-volume set, all the same size. Each book is 2 inches thick in the pages, and have a hard cover that is 1/8 of an inch thick. A bookworm eats through the books from page 1 of the first book to the last page of the last book. How many inches of book did the bookworm eat?

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