Way, Way, Way Past Due

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Way, Way, Way Past Due

December 7, 2014

When you borrow a book from the library, you need to bring it back within a few weeks so other people can borrow it, too. But sometimes people return their library books late — really, really late. Someone just found a library book that had been checked out for 65 YEARS! On top of it, it was found at the opposite end of the country. Wayne Hachey of Maine tripped over a copy of the famous book Gone with the Wind in his dad’s attic, and saw that it was a library book from John Rodgers High School out in Spokane, Washington. It was originally checked out in 1949, and at their late fee back then of 2 cents per day, it owed a $475 fine. However, the library didn’t make him pay the fine, because the book was printed in 1946 and is worth $350, since it’s so old and special. Clearly the library is happy to have it back!

Wee ones: What shape is the cover of most books, including this one?

Little kids: If Wayne had kept the book for another year to read it, how many years late would it have been?  Bonus: If you owe 2 cents each day a book is late, how much do you pay for a whole week?

Big kids: Which year was longer ago, 1946 or 1949? By how many years?  Bonus: Given that, how many years older than you is this book?

The sky’s the limit: If instead your library fine is 1 cent the first day, then another 2 cents for the 2nd day, then another 3 cents for the 3rd day…how much would you owe after 20 days? Do you know a trick to solve this?

 

 

 

Answers:
Wee ones: A rectangle.

Little kids: 66 years.  Bonus: 14 cents.

Big kids: 1946 was 3 years earlier.  Bonus: Different for everyone…the book is 65+3 years old, or 68 years, so subtract your age from 68.

The sky’s the limit: When you add any long series like 1+2+3…+9+10+11…to 20, the numbers pair off: here the 10+11 add to 21, the 9+12 add to 21, the 8+13 add to 21…you end up with 10 sets of 21, which is 210 cents or $2.10. That’s one reason the formula for these “triangle numbers” (since you can stack each number of balls in rows to make a triangle) is the biggest number times 1 more than itself, divided by 2.

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking while still in diapers, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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