One Sharp State

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.

One Sharp State

July 9, 2019

Arizona is home to the world’s most famous hole in the ground (The Grand Canyon). But did you know it’s also the only state with the famous saguaro cactus? These giant cacti can grow up to 60 feet tall, which is 2-3 times as tall as a house! It takes a long time to get there: a saguaro might take 10 years to grow just 1 inch tall. Luckily, saguaros can live for more than 150 years. They don’t grow their first “arm” until they’re at least 75 years old, and some never grow arms at all (those cacti are called “spears”). To suck up lots of water, they spread their roots as far as their height – up to 60 feet away. The largest saguaros can hold 2 tons of water, about the same weight as a big car. But they’re very prickly, so check them out with your eyes, not your hands!

Wee ones: Animals love saguaros. If jackrabbits, mule deer, and bighorn sheep munch on the cactus, how many types of animals is that?

Little kids: If you see 3 saguaros and they each have 3 arms, how many arms are in the patch? Bonus: Saguaro cacti grow fruit in June, which people knock off using 16-foot tall poles. If you hold that pole 6 feet above the ground pointing straight up, how high can its top reach?

Big kids: The largest Saguaro ever measured was a 78-foot tall spear! How much taller is that than you? Bonus: If a saguaro grows its first arm on its 75th birthday, then grows another new arm every 6 years, how many arms will it have on its 100th birthday?

The sky’s the limit: If a saguaro weighs 3,000 pounds and all but 5% of that weight is water, how many pounds of water are in the cactus?

 

 

 

 

 

 

 

 

Answers:
Wee ones: 3 animals eat the saguaro.

Little kids: 9 arms. Bonus: 22 feet tall, because 6 + 16 = 22.

Big kids: Different for everyone, but at least 71-72 feet taller than most people! Subtract your height in feet and inches from 78 feet. Bonus: 5 arms, because it grows 4 additional arms in the 25 years between 75 and 100: on its 81st, 87th, 93rd, and 99th birthdays.

The sky’s the limit: 2,850 pounds. One of the easiest ways to calculate 5% of a number is to first figure out what 10% is, then cut that 10% in half. 10% is 1/10 of 3,000, which = 300, and 1/2 of 300 is 150. 3,000 – 150 = 2,850.

Up next, we visit the state that’s really a blast – at least every 91 minutes.

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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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