Top Pick

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.

Top Pick

October 18, 2014

If you’ve ever played with a calculator, you might have seen that some screens make the numbers using all straight lines, and those numbers look like letters when turned upside down: for example 7738 becomes “BELL” when flipped over. But even when they stay right side up, numbers made of sticks give you all kinds of games to play. Here in this picture we see 9 numbers, laid out 3 across and 3 up and down — and if you move just 1 toothpick from one number to another number to change both, you can make every up-and-down set add up to the same number, and every row running across add up to that same number, too. Can you spot it and solve the puzzle? Read on to do more math tricks with picks!

Wee ones: What’s the biggest number you see on the board?

Little kids: What do the 3 numbers in the top row add up to?  Bonus: If you could change any number in that row to a 9, what’s the biggest total you’d get, and which one would you have to change? (By the way that isn’t the mystery toothpick.)

Big kids: Do you see any other rows or columns that add up to the same as the top row?  Bonus:And now for our challenge…can you figure out which toothpick you can move to change 2 numbers and make all totals across and down add to the same number?




Wee ones: 8.

Little kids: 10.  Bonus: If you change the 1 to a 9 you get your biggest jump, to 18.

Big kids: Yes: the bottom row, and the rightmost column.  Bonus: If you take away the toothpick in the middle of the 8 (in the center box) and use it to make the 6 just to its left into an 8, now that row has 8+0+2 = 10, the left column now has 1+8+1=10, and the center column now has 4+0+6=10.

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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 before she could walk, 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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