Eight (Legs) Is Enough

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.

Eight (Legs) Is Enough

August 15, 2014

Since we’re in the 8th month of the year, it’s a fine time to talk about our 8-legged friend the octopus. It’s an animal that’s been around for nearly 300 million years, and maybe that’s why it’s become pretty smart for a slimy sea creature. Octopuses can find their way through mazes, solve puzzles and take toys apart. They can also remember the answers to these games afterwards. To do these tricks octopuses use their huge brains, which don’t sit just in their heads — 2/3 of an octopus’ neurons stretch down into its arms, enabling some arms to work on one thing while other arms “think” about something else. They also have three hearts to pump their blood, which is blue. It’s clear the octopus is a talented animal; we humans have enough trouble keeping track of 1 heart and 2 feet!

Wee ones: When an octopus swims, 1 of those 3 hearts stops beating, which is why octopuses get so wiped out by swimming and would rather crawl. How many hearts are left beating?

Little kids: If an octopus has 8 arms and you have 2, how many arms do you have together?  Bonus: If an octopus is using 3 arms to build a Lego house and 3 arms to eat shellfish, how many arms are left to work on something else?

Big kids: If a bunch of people and octopuses are swimming in the ocean and together they have 26 arms, what are all the combinations of octopuses and people that could make that total? (Assume there’s at least 1 of each.)  Bonus: A female octopus can lay up to 400,000 eggs at one time. If they all hatch and survive, how many arms do they have all together?

 

 

 

Answers:
Wee ones: 2 hearts.

Little kids: 10 arms total.  Bonus: 2 arms.

Big kids: 3 combinations: 1 octopus and 9 people (for the remaining 18 arms); 2 octopuses and 5 people (for the remaining 10 arms); and 3 octopuses and 1 person.  Bonus: 3,200,000 arms.

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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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