Scouting for Some Cookies

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.

Scouting for Some Cookies

February 3, 2014

It’s Girl Scout cookie season again, when Girl Scouts all across America sell boxes of classic chocolaty Thin Mints, peanut buttery Tagalongs, and coconutty Samoas. Part of the money from these sales helps the Girl Scouts do their projects and good works. All the boxes are about the same size so they’ll stack well in the truck (and on your kitchen table), but there’s a different number of cookies in each one…Thin Mints just sit on top of each other in two tall tubes of plastic wrap, but the Samoas have to sit in a tray so they won’t break. So if want to buy as many Girl Scout cookies as possible, you’ll have to do the math right.

Wee ones: What different shapes are the cookies you see above?

Little kids: If you stack cookies on a plate and they’re all Tagalongs except every 3rd cookie is a Shortbread, how many Shortbreads do you have on a plate of 9 cookies?  Bonus: The Samoa box says that a serving is 2 cookies, and there are 8 servings in the box. How many cookies come in that box?

Big kids: If you have 2 stacks of Thin Mints in the box and one has 2 more cookies than the other, and together they have 24 cookies, how many Thin Mints are in each stack?  Bonus: If the Girl Scout troops in your area fall into a pattern, where one troop sells 4 boxes, the next troop sells 10 boxes, the next sells 22 boxes, and the next sells 46 boxes…how many boxes does the next troop sell?

The sky’s the limit: Some Girl Scouts sell a lot of boxes of cookies. If a Girl Scout sells either 8, 15, or 19 boxes of each flavor, what combination of amounts could she sell that comes closest to 100 boxes total – given that there are only 9 flavors?

 

 

 

Answers:
Wee ones: Mostly circles, plus a 4-leaf clover (4th from left) and a hexagon with a hole (3rd from right).

Little kids: 3 Shortbreads.  Bonus: 16 cookies.

Big kids: 11 Thin Mints in one, 13 in the other.  Bonus: 94 boxes, because the pattern is to double the previous number and add 2.

The sky’s the limit: Lots of answers come close…for instance, 5 flavors of 19 boxes each comes to 95, and 8 more boxes of 1 more flavor brings it to 103 boxes, which is even closer to 100. Then there’s 5 sets of 15 (comes to 75) plus 3 sets of 8 (another 24), which comes to 99. But one winning combo is 5 sets of 8 (40) plus 4 sets of 15 (another 60), for a total of 100 boxes. And there’s another: 4 sets of 19 each gives you 76, plus 3 sets of 8 (for 24) gives you exactly 100 also. Can you come up with any others?

And a big thank-you to Sophia and Kathleen M-G for bringing this topic to us!

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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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