A Very Prickly Family

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.

A Very Prickly Family

September 12, 2019

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Porcupines aren’t the only prickly animals out there. Hedgehogs, which aren’t related to porcupines at all, are spiky too, with more than 6,000 quills on some of them! Hedgehogs protect themselves by rolling up into a ball, which makes all the spines stick straight out. That said, even hedgehogs can be lovable. A batch of 4 baby hedgehogs lost their mom, but a mama tabby cat named Sonya adopted them alongside her own kitten. They snuggle together, nap together, even eat together. The baby “hedgekittens” look very cute even with all those prickles….just be careful when you try to pet them.

Wee ones: If Sonya has 1 kitten plus the 4 baby hedgehogs, how many “kids” call her Mom?

Little kids: If we have Sonya and her kitten, and the 4 baby hedgehogs, how many more hedgehogs than cats are there in this funny family?  Bonus: A group of hedgehogs is called a “prickle” — really! If you added 7 more hedgehogs to these 4, how many would you have in your prickle?

Big kids: Porcupine quills are easy to pluck, but hedgehog quills aren’t. If a porcupine has 30,000 quills, how many more does it have than a 6,000-quill hedgehog?  Bonus: How many hedgehogs together would you need to have the same number of quills as the porcupine?

The sky’s the limit: If you have cats, porcupines and hedgehogs, and the number of cats plus porcupines is 14, the number of cats and hedgehogs is 18, and the number of porcupines and hedgehogs is 20, how many of each animal do you have?








Wee ones: 5 “kids.”

Little kids: 2 more. (4 vs. 2).  Bonus: 11 hedgehogs.

Big kids: 24,000 quills.  Bonus: 5 hedgehogs. 30,000 divided by 6,000 is 5, since 30 divided by 6 is 5.

The sky’s the limit: 6 cats, 8 porcupines and 12 hedgehogs. Adding hedgehogs to the cats instead of porcupines raises the total by 4, so there are 4 more hedgehogs than porcupines. That means if you had the same number of hedgehogs as porcupines, that total would drop from 20 to 16. There would be equal numbers of each, so the porcupines would be half, giving us 8 porcupines. But there were 4 more hedgehogs than porcupines, giving us 12 hedgehogs. And the porcupines plus cats add up to 14, so there are 6 cats.

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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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