The post Catch It by the Tail appeared first on Bedtime Math.

]]>It must be fun to have a tail. You can swing it around, smack things with it, and if you’re a possum, hang from tree branches with it. You can even measure using tails: as Bedtime Math fan Nhya points out, in the *Warrior Cat* book series they measure cats in tail lengths, which equal 1 foot. But which animals out there have the longest tails? As you would think, big cats have longer tails than housecats, with lions having tails up to 41 inches long — almost 3 1/2 feet. But we can go bigger. A giraffe’s tail looks short and cute on its owner, but can be up to31 inches long, and elephant tails can reach 51 inches — that might be taller than you! Of course, if you think of a worm as one big squiggly tail, the winner is the bootlace worm, the longest animal on earth: it can grow to 180 feet long. No matter how much of that counts as tail, it’s going to be longer than anyone else’s!

*Wee ones:* Who has the *shorter* tail, a girl cat with an 8-inch tail or a boy cat with a 12-inch tail?

*Little kids:* If a 3-foot alligator has a 3-foot tail, how long is the whole animal? *Bonus:* If you have a pet giraffe with a 31-inch tail, a lion with a 41-inch tail, and an elephant with a 51-inch tail…what tail length would come next to follow the pattern?

*Big kids:* If a cat tail length is 12 inches, how long is a Warrior Cat who is 3 tails long? *Bonus:* Who is taller, an elephant’s 51-inch tail or you — and by how much? (Reminder: A foot has 12 inches.)

*The sky’s the limit:* If the bootlace worm can count 160 feet of itself as “tail,” how many times would a possum’s 15-inch tail have to double in length to match that? It works out perfectly…

Answers:

*Wee ones:* The girl cat at 8 inches.

*Little kids:* 6 feet. *Bonus:* A 61-inch tail, if we can find one.

*Big kids:* 36 inches. *Bonus:* Different for everyone…take your height in feet and inches, and subtract 51 from it, or subtract it from 51.

*The sky’s the limit:* You double it 7 times. 15 inches doubles to 30 inches, which then doubles to 60 inches – which is exactly 5 feet. From there we double it to 10, 20, 40, 80, and finally 160 feet. Another way to solve: 15 inches is 1 1/4, feet, which doubles up to 2 1/2 feet and then 5 feet, and so on.

And thank you Nhya L-G for this great math topic!

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]]>The post Last Chance for Pumpkins appeared first on Bedtime Math.

]]>Thanksgiving is over and fall is about to turn into winter, at least for people living on the north half of our planet. So what do you do with all those leftover pumpkins? You can make breads, pies, and soup with the fleshy part, but you’re still left with those giant gobs of goopy seeds inside. The good news is, you can turn that goop into a tasty, crunchy snack: roasted pumpkin seeds. How? Rinse them under running water to rub off all the stringy fibers. Once the seeds are dry, have a grown-up heat the oven to 400 degrees, and spread the seeds on a lightly greased baking sheet. Bake them for 15 minutes, then sprinkle them with whatever seasonings you like: salt, sugar, cinnamon, chili powder, a squirt of lime. Then you just have to decide what to do with the rest of that 80-pound pumpkin.

*Wee ones:* If you sprinkle a pumpkin seed with salt, then the next with sugar, then the 3rd with cinnamon, then start over with salt, then sugar, then cinnamon, then salt…what’s next?

*Little kids:* If you scoop out 8 slippery pumpkin seeds but 3 of them squirt onto the floor, how many are left in your hand? *Bonus:* If you have 3 big pumpkins and each one has 200 seeds inside, how many seeds do you have for roasting?

*Big kids:* If you start roasting your seeds at 3:20 for 15 minutes, at what time do they finish? *Bonus:* If you want to roast 300 seeds and every pumpkin has 80 seeds, at least how many pumpkins will you need to scoop enough seeds?

Answers:

*Wee ones:* Sugar.

*Little kids:* 5 seeds. *Bonus:* 600 seeds.

*Big kids:* At 3:35. *Bonus:* 4 pumpkins, since the first 3 will give you only 240 seeds.

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]]>The post Dogs Who Love Sleds appeared first on Bedtime Math.

]]>Usually when we ride around on wheels, either we’re doing the work, like on a bike or skateboard, or the vehicle does the work, like a car. But there’s a 3rd choice: have animals do the work. Bedtime Math fan Symone B. went to Alaska and got to see huskies pull dogsleds in Denali National Park. No vehicles with motors are allowed there, so they use huskies to carry people, food and other supplies around the park. Huskies luuuuuv to work hard, and actually jump and romp around when it’s time to hook up to the sled — they find it that exciting. Dogsled teams can run up to 150 miles a day for up to 17 days in a row! Symone’s sled carried 500 pounds of people and other stuff, and the dogs easily pulled it at 25 miles per hour, as fast as that car. We hope those huskies enjoyed a nice big dinner after that.

*Wee ones:* If you and 6 dogs go riding, how many animals is that in total?

*Little kids:* If 5 100-pound kids load onto a sled, what numbers do you say to count up the weight as they get on? *Bonus:* If 7 dogs pull your sled, 1 lead dog will pull in front, followed by the rest of the dogs in 2 equal lines. How many dogs are in each line?

*Big kids:* Symone points out that 1 year for us is like 7 years for a dog. How many dog days are 4 of our days? *Bonus:* If the dogs start running today (Friday) and run 17 days total, on which day of the week would be their 17th day? (Remember to count today as their 1st day!)

Answers:

*Wee ones:* 7 animals.

*Little kids:* 100, 200, 300, 400, 500. *Bonus:* 3 in each line, to make 6 following the lead dog.

*Big kids:* 28 days. *Bonus:* On a Sunday.

And thank you Symone for the beautiful dog pictures you took!

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]]>The post A Very Thirsty Turkey appeared first on Bedtime Math.

]]>It’s Thanksgiving, that American holiday when we show our thankfulness for food, mostly by eating too much of it at once. People have all kinds of favorite foods for Turkey Day: turkey, of course, plus bready stuffing, cranberries, sweet potatoes, green beans, pumpkin pie… But no matter which of those foods you choose, what ingredient shows up in all of them? Water. Not only do wheat, squash and other plants need water to grow, but animals like turkeys drink water themselves, and they eat *plants*, which need water. Scholastic SuperScience Magazine added it all up, and figured out that *hundreds* of gallons of water go into the meal on your plate. One serving of turkey alone drank up 116 gallons of water along the way, between the thirsty bird and the thirsty plants it ate. That’s 3 or 4 full bathtubs. Let’s find out where else the water shows up!

*Wee ones:* If you eat stuffing, turkey, sweet potato, beans, and pumpkin pie, how many foods do you eat that aren’t animals?

*Little kids:* Your sweet potatoes probably drank up 7 gallons of water along the way, but your much drier wheat roll used 9 gallons. How much more water did the wheat use? *Bonus:* How many servings of each would give you a total of 23 gallons?

*Big kids:* They say almonds, which grow on trees, suck up 98 gallons of water per serving, while a serving of cranberries uses up only 2 gallons. How much water do those servings use together? *Bonus:* How many times as thirsty are those almonds compared to the cranberries?

*The sky’s the limit:* Does the 116 gallons for that serving of turkey make sense? If a turkey lives 10 years, drinks 1 cup of water each day, and eats another cup of water through its food, about how many gallons of water did your serving use if that turkey feeds just 10 very hungry people? (Hint if needed: there are 16 cups in a gallon, and 16 = 2 x 2 x 2 x 2, so to divide by 16 you can just cut it in half 4 times in a row.)

Answers:

*Wee ones:* 4 foods, it would be 5 including the one animal.

*Little kids:* 2 gallons more. *Bonus:* 2 7’s and a 9, which is 2 sweet potatoes and 1 wheat roll.

*Big kids:* 100 gallons. *Bonus:* Almonds use 49 times as much water.

*The sky’s the limit:* That would give us about 45 gallons. 2 cups of water a day for 10 years, or about 3,650 days, comes to 7,300 cups. Since you’re then dividing it among 10 people, that’s 730 cups per person. There are 16 cups in a gallon, so we need to divide that 730 into 16-cup chunks. Let’s cut in half 4 times in a row: we get 365 (remember that number?), then round off to 364 to give us 182, then 91, then finally round again to get 45 gallons. If turkeys are thirstier than that, then the number goes up. But most turkeys can feed up to 20 people, which would lower the number. Either way, it’s a lot of water!

And thank you Ellie L. for sharing this story with us!

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]]>The post The Truth about Road Signs appeared first on Bedtime Math.

]]>If you’re traveling today for the big holiday weekend, you’ll see all kinds of road signs telling you where you are and what to do, like stop or slow down. Most signs are easy to read, and that’s because those letters on them are HUGE. They are way bigger than you think, because the signs are far away and high above our heads. Your cute little red stop sign at the corner is actually a 2 1/2-foot tall octagon, almost half the height of a grown-up, and the letters are twice as tall as your hand. On a big green highway sign, the blue and red interstate number is bigger than that whole stop sign, and the highway sign itself can be 10 or 12 feet tall! If you ever stand next to a sign that’s down on the ground, you’ll find that some letters and numbers are just as tall as you.

*Wee ones:* A stop sign is octagon-shaped: it has a top and bottom, a left side and right side, and 4 angled sides where a square would have corners. How many sides is that?

*Little kids:* The letters on a stop sign are about 10 inches tall. If your hand is 5 inches long, how much taller are those letters? *Bonus:* If you reach a stop sign at 2nd Avenue, then 5th Ave, then 8th Ave….when do you think you’ll see a stop sign next?

*Big kids:* In the photo, that little red, white and blue highway number shield is 3 feet tall! If the sign is 4 times as tall as that plus 2 more feet, how tall is the whole sign? *Bonus:* If those interstate highway numbers are exactly 3 feet tall, how does that stack up against your height? (Reminder if needed: 1 foot has 12 inches).

Answers:

*Wee ones:* 8 sides.

*Little kids:* 5 inches. *Bonus:* At 11th Avenue, because there’s a sign at every 3rd street.

*Big kids:* 14 feet tall. *Bonus:* Different for everyone…subtract 3 feet from the “foot” part of your height in feet and inches, or subtract 3 x 12 (which equals 36) from your height in inches.

The post The Truth about Road Signs appeared first on Bedtime Math.

]]>The post Trip to the Center of the Earth appeared first on Bedtime Math.

]]>What happens if you dig a hole straight down into the ground? How far do you have to dig to reach the bottom? That’s what Bedtime Math fan Ajax wants to know. Well, it depends what you mean by the “bottom.” If you just want to dig to the center of the Earth, it’s 3,958 miles to the very middle of that ball. But if you want to dig as far as you can until you show up on the other side, it will be twice as far, or 7,916 miles. The crazy thing is, the deepest humans have ever dug is just 7 1/2 miles, or less than 1/1000th of the way across! By the way, there’s a website called FreeMapTools where you mark your starting point, and it will show you the spot exactly on the other side of Earth where you would pop out. Just remember that if you do try this, the center of Earth is a 10,000-degree F blob of iron and nickel, so you’ll need your heat suit.

*Wee ones:* If you dig 7 miles down, then dig 1 more mile to beat the record, how far do you dig?

*Little kids:* Which is cooler, 1 thousand degrees or 10 thousand degrees? *Bonus:* Earth is 7,916 miles across. Close your eyes and see if you can remember that number!

*Big kids:* Who digs farther, you if you dig down 6 miles a day for 6 days, or your friend who digs 5 miles a day for a whole week? *Bonus:* If you dig exactly 20 miles every day, by how much will you overshoot the exact middle spot at 3,958?

*The sky’s the limit:* If you dig 10 miles the first day, 10 miles again the 2nd day, then 20 the 3rd day, then 30, then 50… how many miles do you think you dig the day after that?

Answers:

*Wee ones:* 8 miles.

*Little kids:* 1 thousand degrees. *Bonus:* 7,916…7,916….see how long you can remember that.

*Big kids:* You dig farther, at 36 miles vs. your friend’s 35. By the way that happens with any number multiplied by itself (squared): the answer will be 1 more than multiplying that number plus 1 by that number minus 1. Try it! *Bonus:* Just 2 miles, since 3,960 will be a multiple of 20.

*The sky’s the limit:* 80 miles. If you noticed the pattern, each ay you dig as far as the previous two days added together. It’s the famous Fibonacci series multiplied by 10, where the Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13…

And thank you Ajax for digging into math with us!

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]]>The post Fat Dog appeared first on Bedtime Math.

]]>When you eat a lot of junk food and not enough healthy food, you get fat. And the same thing happens to dogs. Just 2 years ago Dennis the dachshund weighed 56 pounds, which is about 4-5 times as much as a dog like him should weigh. He had been eating fast food hamburgers and pizza — not just human food, but really unhealthy human food. It really made him blow up like a blimp. Think how sad that must have been: no running, no jumping up on the couch, no chasing after cats and squirrels. The good news is, his owner’s relative was so worried about him that she adopted him as her own pet. She put him on a diet, meaning she changed the types of foods Dennis ate. Thanks to eating right, Dennis lost 3/4 of his weight! Now his body is so much smaller, although not his floppy ears or long snout – they’re still the right size for a dachshund. And Dennis can finally chase cats again.

*Wee ones:* If Dennis eats pizza, then a burger, then a bowl of ice cream, which food did he eat 2nd?

*Little kids:* If Dennis ate burgers 3 days a week and pizza the other days, how many days did he eat pizza? *Bonus:* If he ate twice a day every day, how many junk-food meals did he eat in a week?

*Big kids:* Before his new diet, what did Dennis weigh compared to *you*? *Bonus:* If Dennis weighed 4 times as much as he should have, what does he weigh now? (Hint: To divide a number by 4, you can just cut it in half, then cut it in half again.)

Answers:

*Wee ones:* The burger.

*Little kids:* 4 days. *Bonus:* 14 fatty meals.

*Big kids:* Different for everyone…subtract 56 from your weight in pounds, or even more scary, subtract your weight from Dennis’ 56! *Bonus:* 14 pounds.

The post Fat Dog appeared first on Bedtime Math.

]]>The post Time to Line Up… appeared first on Bedtime Math.

]]>When you look at a digital clock, do you get excited when a cool number show ups? Like a time when all the digits are the same, or when the first two add up to the third? Only a few times each day does the clock do fun tricks like that. On a long car trip, Bedtime Math fans Miriam, Silas, and Titus R. decided to count up how many cool times clocks can show us. They figured out how many times the clock shows all one digit, like 1:11, 2:22…and remembered that those times all show up in the morning, then again in the afternoon. Can you figure out how many times have all the same digit? Let’s find out how many other cool times are worth waiting for — and how often to check the clock to catch them.

*Wee ones:* A clock shows the numbers 1 to 12 on it. Can you name all the numbers between 1 and 12?

*Little kids:* If the time is 5:55, what was the last time before that when all the digits were the same? *Bonus:* Times like 2:35 are cool too, because the numbers can be an equation: here it’s 2+3=5. What equation is happening in the times 7:34 and 2:48?

*Big kids:* How many different times in one day does the clock show all the same digit, like 3:33? *Bonus:* What’s the longest you have to wait between two of those times?

*The sky’s the limit:* What’s the longest you have to wait between times where the first two digits add up to the third — and there’s no 4th digit?

Answers:

*Wee ones:* 2, 3, 4, 5, 6, 7, 8 ,9 ,10, 11.

*Little kids:* 4:44. *Bonus:* We’re subtracting in the first: 7 – 3 = 4. And we’re multiplying in the second: 2 x 4 = 8.

*Big kids:* There are 12 times in one day: 1:11, 2:22, 3:33, 4:44, 5:55, 11:11 in the morning, and then those 6 times repeat in the afternoon. *Bonus:* The gap from 5:55 to 11:11, which is 5 hours 16 minutes (5 hours to get to 10:55, then another 5 minutes to get to 11:00, then another 11 minutes).

*The sky’s the limit:* 3 hours 52 minutes. The earliest time in the day that does this, using the smallest numbers, is 1:01. The latest time is 9:09 since you can’t do 9:90 (only 60 minutes in an hour). Many times work during each of the hours in between, so our biggest wait will be the multi-hour jump from 10:00 through 12:59. So we’re going from 9:09 am to 1:01 pm. That’s 8 minutes less than 4 hours, or 3 hours 52 minutes.

And thank you Miriam, Silas and Titus for sharing this great waiting game!

The post Time to Line Up… appeared first on Bedtime Math.

]]>The post When There’s Wind in the Wires appeared first on Bedtime Math.

]]>You’ve probably seen pictures of cute old-fashioned windmills, or seen a toy one spinning at the miniature golf course. Today’s windmills aren’t as cute and charming, but they’re a lot bigger and stronger, and give us a lot more electricity. They’re called wind turbines, and they are *huge*: their propeller blades can be up to 200 feet long, and can slice through the air at 180 miles an hour! So it’s no surprise how much power these machines can give us. As the wind turns the spinny blades, the machine turns that energy into electricity, which is then sent into the “grid” and through the wires to our houses. You know how a light bulb uses around 60 watts? Well, these wind turbines can generate 1*million* watts, enough power for hundreds of houses at once. If you group a bunch of turbines into a “wind farm,” you can power whole towns. Now you’d just better hope the wind keeps blowing.

*Wee ones:* Which is faster, a 14-mile-per-hour wind or a 9-mile-per-hour wind?

*Little kids:* If your home uses 10 light bulbs total, but you build your own little windmill that can power 6 more bulbs, how many bulbs can you have now? *Bonus:* The 6 closest turbines in the photo have 3 blades each. How many blades do they have in total? See if you can count up by 3s!

*Big kids:* If the tower holding up the blades is 263 feet tall to the center, and the blades are another 100 feet long, how high off the ground could you swing if you could ride on the tip? *Bonus:* Just 1 wind turbine can capture enough wind power to run about 500 houses! If you build a farm of 30 turbines, how many houses can you power? (Hint if needed: How many could you power with just 3 turbines?)

Answers:

*Wee ones:* The 14-mile-per-hour wind.

*Little kids:* 16 light bulbs. *Bonus:* 18 blades: 3, 6, 9, 12, 15, 18.

*Big kids:* 363 feet. *Bonus:* 15,000 houses!

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]]>The post Math-y Moustaches appeared first on Bedtime Math.

]]>When a man grows a moustache or beard, suddenly he has all this extra hair to trim and comb and shampoo. But some guys take it even a step farther. At the National Beard and Moustache Championships, more than 300 people showed up to show off the craziest facial hairstyles you’ve ever seen. They tried to win for best Musketeer beard, best Lumberjack, best Fu Manchu, and many other categories. Some styles used great “geometry,” which is the math of shapes. The guy shown on the left here shaped lots of circles into his moustache and beard, and the second guy formed ribbons that look like a “Moebius strip,” that weird shape where an ant has to travel all the way around twice to reach its starting point again. You can make your own Moebius strip easily: cut out a long, narrow rectangle of paper, bring the ends together to make a circle, but then flip one end over before stapling or gluing to give the circle a twist.Then imagine wearing that on your face!

*Wee ones:* How many circles can you count in the guy-on-the-left’s moustache and beard?

*Little kids:* If 2 of those 10 circles go down the middle and the rest are split evenly between left and right, how many circles are on each side? *Bonus:* If circle guy started growing this beard 4 months before the November competition, in what month did he start?

*Big kids:* If of the 300 contestants 50 had just moustaches, 100 had just beards, and the rest had both, how many people in total had *at least* a moustache? *Bonus:* If these are just 2 of the 300 contestants, how many other guys went to the competition?

Answers:

*Wee ones:* 10 circles, counting the little ones on each tip of the moustache.

*Little kids:* 4, since you’re dividing 8 circles into 2 equal groups. *Bonus:* In July.

*Big kids:* 200 people, since 150 had both and 50 had just a moustache. Or you could just subtract the 100 beard-only guys from the 300 total. *Bonus:* 298 other crazy-looking people.

The post Math-y Moustaches appeared first on Bedtime Math.

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