When Your Tail Really Counts

When Your Tail Really Counts

March 9, 2020

Looks like these ring-tailed lemurs really want to learn how to use that camera. And it turns out these silly, stripy goofballs are pretty smart: they can do math! Lemurs can count, add, and subtract, and can also line up objects in order from memory. Even their wild long tails have numbers behind them: the lemur’s tail always has 12 or 13 white rings and 13 or 14 black rings, and the tip always ends in black. Lemurs live on the island of Madagascar off the coast of Africa. It’s a beautiful place, so we can see why they’d like to take some pictures of it!

Wee ones: If the lemur’s tail has a black ring at the tip, then white, then black, then white, what’s the next ring?

Little kids: If a lemur’s tail has 12 white rings and 13 black rings, of which color does it have more?  Bonus: If the 1st ring is black followed by white, then black, then white, and so on, what color is the 12th ring?

Big kids: If a lemur’s tail has 27 rings, and there’s 1 more black ring than white ring, how many rings of each color?  Bonus: If a lemur is 18 inches long and its tail is another 1/3 body length longer than that, how long is the whole lemur from head to tail tip?

The sky’s the limit: We can’t tell you how many rings a baby lemur’s tail has, but if you took that number, multiplied it by itself, and added 9, you’d get 58. How many rings does the tail have?

Wee ones: A black ring.

Little kids: More black rings.  Bonus: White.

Big kids: 14 black rings and 13 white.  If you took off that extra black ring, you’d have 26 rings that are equally black and white, so then you just cut 26 in half to find the white.  Bonus: 42 inches, since it’s 18 plus 24.

The sky’s the limit: 7 rings.  If you walk backwards, the number times itself comes to 49 (58-9), and 49 is divisible only by 7, so that’s your answer!

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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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