The Missing Piece

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.

The Missing Piece

January 31, 2013

Jigsaw puzzles offer that perfect balance of fun and frustration.  The more squiggly-shaped pieces you have, the harder it is to finish it, but the more awesome you feel when you finally do.  What really matters is the size of the pieces compared to the size of the designs: if an apple uses up just 4 pieces, that’s pretty easy, but that same apple made up by 40 pieces will be much harder.  Then there are those pieces that look like they should fit together but don’t.  And just to make things interesting, there’s always the one piece that’s missing from the set.  But even with all these challenges, somehow we stick to it till we get every piece possible in place.

Wee ones (counting on fingers): The world’s largest jigsaw puzzle has over 32,000 pieces!  It’s 17 feet long and 6 feet wide when put together.  If you lay down across it the short way, how many feet wider than you is it? (You can round your height to the nearest foot.)

Little kids: If your jigsaw puzzle is 10 pieces across by 6 rows tall, how many puzzle pieces should you have in total?  Bonus: Say the vacuum sucked up 3 pieces, your dog ate 2 pieces, and 5 pieces got mixed into some other puzzle box.  How many pieces do you actually have?

Big kids: A common approach to puzzles is to build the border first, then fill in the inside pieces.  If there are 60 pieces on each long side of the puzzle and 20 on each short side, how many total edge pieces does the puzzle have? (Remember that there are two long sides and two short sides – and don’t double-count the corners!)  Bonus: If the puzzle pieces are all in neat rows and columns following those edge pieces, how many inside pieces are there?




Wee ones: Different for everyone…subtract your height from 6 feet.

Little kids: 60 puzzle pieces.  Bonus: You are missing a total of 10 pieces, so you actually have 50 puzzle pieces.

Big kids: 156 edge pieces: there are 120 long-edge pieces and 40 short-edge pieces, but then you take away the 4 corner pieces because the long edges counted them already.  Bonus:There are 1200 pieces total…so if you take away the 156 edge pieces, you have 1,044 pieces in the middle.

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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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