The post The Bungee Dunker appeared first on Bedtime Math.

]]>Bungee jumping is that crazy sport where you hook a long, stretchy bungee cord onto a bridge or cliff, then jump off while hanging onto it. If you do the math right, you zoom downward until the cord stretches as much as it can…you slow to a stop, then snap back up towards the sky again. If you do the math wrong, you go SPLAT on the ground. To keep this from happening, you leave yourself extra room at the bottom. Well, not this guy. Simon Berry left a cup of tea on a diving board, then bungee-jumped from more than 240 feet above and perfectly dunked a chocolate cookie in it. He had to get far enough down to reach it, but without crashing headfirst into it. But as we see in the video at the bottom, the cookie did make a big splash!

*Wee ones:* Hold 2 things that won’t break, like a stuffed animal and a bouncy ball. Hold one thing in each hand and drop them from the same height at the same time. Do they reach the ground at the same time? See what happens!

*Little kids:* If Simon counted down the last 5 seconds before jumping, what numbers did he say? *Bonus:* If he took 5 seconds to fall and dunk the cookie, then 5 seconds to snap back up, how many seconds did his whole bungee trip take?

*Big kids:* Simon fell 240 feet 10 inches, then zoomed back up 240 feet 10 inches. How far did he zoom through the air in total, in feet and inches? *Bonus:* If halfway down Simon started screaming in panic, how much farther did he have left to fall to reach the cup of tea?

*The sky’s the limit — literally:* If your bungee cord lets you fall 1 foot the 1st second, then 3 more feet during the 2nd second, then 5 more feet during the 3rd second…will you fall 49 feet in a round number of seconds? And can you tell quickly without adding up all the numbers?

Answers:

*Wee ones:* Unless one of the things you drop catches air and floats (like a piece of paper), they should hit the ground at the same time!

*Little kids:* 5, 4, 3, 2, 1! *Bonus:* 10 seconds.

*Big kids:* 481 feet 8 inches, since he fell 480 feet plus 20 inches. *Bonus:* 120 feet 5 inches.

*The sky’s the limit — literally:* Yes! You might have noticed that each time you add the next odd number, you get a new “perfect square” as the total — a number that is some other number times itself (1×1, 2×2, 3×3, and so on). You get 1 foot in total, then 4 feet total after 2 seconds, 9 feet after 3 seconds…so you’ll reach 49 feet in 7 seconds.

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]]>The post A Day for Sweet Teeth appeared first on Bedtime Math.

]]>As we’ve seen, Americans totally pig out on special days, like Thanksgiving and Super Bowl Sunday — and Valentine’s Day. The chocolate adds up fast for all 320 million of us Americans. Together we will send 190 million valentines, not even counting the 15 million love emails and texts. Along with that, we will buy (and eventually eat) 58 million pounds of chocolate, much of it packed in the 36 million heart-shaped boxes we give. Just make sure you don’t eat them too fast!

*Wee ones:* Caramels are usually rectangle-shaped. How many sides does a rectangle have?

*Little kids:* If you get 3 Valentine cards and 2 more boxes of chocolate than that, how many boxes do you get? *Bonus:* If your family sends out 10 cards, and 3 go to kids while 1 goes to your dog, how many cards go to grown-ups?

*Big kids:* If a box of 15 candies has twice as many chocolates as nut chews, how many nut chews are in there? *Bonus:* If you eat one of those 14 chocolates every 5 minutes starting at 2:10 pm, will you finish the whole box by 3:30 pm?

*The sky’s the limit:* 58 million pounds of chocolate for 320 million people isn’t THAT* *much. Is it a whole 1/4 pound per person?

Answers:

*Wee ones:* 4 sides.

*Little kids:* 5 boxes of chocolate. *Bonus:* 6 cards.

*Big kids:* 5 nut chews. Each chew has 2 chocolates with it, so they’re in sets of 3, and there are 5 sets of 3 in 15. *Bonus:* Yes! After eating one at 2:10 pm, you’ll take 13 x 5 = 65 minutes to eat the rest, bringing you to 3:15 pm.

*The sky’s the limit:* It’s not even close. 1/4 pound per person for 320 million people would come to a whopping 80 million pounds. By the way, 1/4 pound is just 4 ounces, or two regular-sized candy bars.

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]]>The post Going Slideways appeared first on Bedtime Math.

]]>When cavemen invented the wheel thousands of years ago, it was probably wood or rock. It probably wasn’t a rubber tire full of air, and they probably didn’t use it to go sledding. That’s called inner tubing: you sit or lie down on a giant donut-shaped balloon, someone gives you a push, and you slide down the snowy, slippery hill. It’s called an “inner” tube because it’s from inside an even bigger circle: a truck tire. Humans first started snow tubing in 1820 in Switzerland, a long time after the cavemen – but a long time before cars and trucks, so where did they get their tubes? More importantly, what happens when you spin as you slide? Lots of math, as you’ll see here!

*Wee ones: *If your inner tube spins once to the left, then once to the right, then once to the left, then once to the right…which way do you spin next?

*Little kids:* If you, 3 friends, and 2 snow-loving dogs all pile onto an inner tube, how many riders are there? *Bonus:* You can also ride tubes on waterslides. If you go 10 miles an hour on snow but twice as fast in water, how fast do you tube on the water?

*Big kids:* If you start sliding facing downhill, with the hill’s right side on your right, and as you slide you spin 1/2 turn to your left, then 1/4 of a turn to your right, then 3/4 turn to the left, which way are you facing now? *Bonus:* If 1/2 the tubes are double tubes (seating 2 people) and the other 1/2 are single tubes, how many tubes are there if they hold 18 people total?

*The sky’s the limit:* If your tube spins once around every 2 seconds, your friend spins once every 3 seconds, another friend spins once every 4 seconds, and the last friend spins once every 5 seconds, what’s the soonest you’ll all face forward at the same time if you all started facing forward?

Answers:

*Wee ones:* To the left.

*Little kids:* 6 riders. *Bonus:* 20 miles an hour.

*Big kids:* Downhill! The 1/2 turn faced you backwards, the 1/4 turn left you facing left, then the 3/4 turn spun you around to the front. *Bonus: *12 tubes in total: 6 singles, and 6 doubles which will seat 12 more people. If 1/2 are single and 1/2 are double, then each double and single forms a pair, and each pair holds 3 people. Then just divide that into the total of 18.

*The sky’s the limit:* In 60 seconds, the smallest multiple of 2, 3, 4 and 5. You don’t need to multiply 2 x 3 x 4 x 5 to get the smallest number, because if it’s divisible by 4, it’s already divisible by 2.

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]]>The post Once upon a Unicorn appeared first on Bedtime Math.

]]>There may be no such thing as a unicorn, but a narwhal comes close. Narwhals are arctic whales that have a long, spiral tusk sticking out from the left side of their mouths. That tusk is actually a reeeeeeally long tooth that can grow over 10 feet long! People may have gotten the idea of unicorns from seeing narwhals pop up out of the water…unicorn horns in drawings from hundreds of years ago look a lot like twisty narwhal tusks. The Vikings thought the tusks even had magical powers. Narwhals can grow to up to 18 feet long, even before you count that tusk…It’s much easier for them to carry a 10-foot tooth than for us!

*Wee ones:* Who’s taller, you or that 10-foot tooth?

*Little kids:* How much taller than you is that 10-foot tusk? Find out your height to the closest foot! *Bonus:* A few narwhals have 2 tusks instead of 1. If there are 9 narwhals but 3 of them are double-tusked, how many tusks are there in total?

*Big kids:* In the summer, narwhals group up by the hundreds. If a group of 600 narwhals has 2 parents and 2 kids in every family, how many kid narwhals are there? *Bonus:* If your front tooth is just 1/4 inch long, how much longer is the narwhal’s 10-foot tooth? (Reminder if needed: A foot has 12 inches.)

Answers:

*Wee ones:* The tooth is taller.

*Little kids:* Different for everyone…subtract your height in feet from 10. *Bonus:* 12 tusks.

*Big kids:* 300 kid narwhals, since 1/2 of all the narwhals are kids. *Bonus:* 119 3/4 inches, or 9 feet 11 3/4 inches.

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]]>The post A New Top Dog appeared first on Bedtime Math.

]]>It’s the final day of the Westminster Kennel Club Dog Show, where our furry friends try to show us they’re the top dog. It’s a tough job. Their handlers attack them with brushes, barrettes and blow-driers to make them look perfect. Then the dogs have to trot around the ring without barking, drooling, or sniffing the other dogs. There are many “breeds” of dog — with different sizes, shapes, colors of fur, and amounts of furriness — and each breed has a perfect look that every dog tries to match. Once dogs win the top prize, they never come back again, so every year we get a new champ! Let’s see who wears the barrettes the best and drools the least.

*Wee ones:* Get on your hands and knees like a dog, and bark exactly 4 times!

*Little kids:* The dogs clump into 7 “groups,” like “Working Dogs” and “Toy Dogs.” If you have 1 pet dog from each group except a Toy Dog, how many pet dogs do you have? *Bonus:* If you had 3 pet dogs, who would have more total legs: the dogs, or you and your family?

*Big kids:* Some dogs come in different sizes, like the miniature, standard, and giant schnauzer. If 20 of each size of schnauzer compete today, how many schnauzers show up in total? *Bonus:* If the 192 breeds EACH had exactly 20 dogs competing, how many dogs would come to the show this year? (*Hint if needed:* multiplying by 20 is the same as multiplying by 2, then by 10.)

Answers:

*Wee ones:* Count your barks: 1, 2, 3, 4.

*Little kids:* 6 dogs. *Bonus:* Different for everyone…the dogs have 3 x 4 = 12 legs, then count up your family’s legs with 2 per person.

*Big kids:* 60 schnauzers. *Bonus:* 3,840 dogs!

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]]>The post The Building That Won’t Fall Over appeared first on Bedtime Math.

]]>Whether they’re small houses or tall skyscrapers, the buildings we live in have nice straight walls to hold up our ceilings. But that’s not true for every building out there. The famous Leaning Tower of Pisa in Italy has been leaning on an angle for more than 600 years, and without falling! It took 199 years to build, starting in 1173, but stood straight for only the first 5 years. As soon as they added the 3rd story, it started tilting. The problem is, the tower is really heavy for its height. It’s only about 183 feet tall, but it weighs 16,000 tons! Worse yet, it was built on soft clay that couldn’t hold up the building. Over the next few centuries, builders kept adding more stories and making changes in hopes of fixing the tower. By 2001 builders gave up and left it as it stands today. After all, if it hasn’t fallen over for more than 800 years, it hopefully never will!

*Wee ones:* Stand up straight, then tilt your body to the left as far as you can. Now tilt to the right!

*Little kids:* The tower now has 7 floors. How many floors did they add after the first 2 good ones? *Bonus:* The first 2 stories were finished in 1173. If it then stood straight for 5 years, when did it start tilting?

*Big kids:* The tower needs 4 more steps to have a full 300. How many steps does it have? *Bonus:* If the tower started tilting in 1178, when did it hit 800 years of tilting?

Answers:

*Wee ones:* See if you can figure out your left from your right!

*Little kids:* 5 more floors. *Bonus:* In 1178.

*Big kids:* 296 steps. *Bonus:* In 1978, just two years after the U.S. turned 200.

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]]>The post Snow Gone Squirrelly appeared first on Bedtime Math.

]]>Humans love playing in the snow, but it looks like squirrels are joining the action, too. We just love this snowmobile-riding squirrel — even he seems surprised about it, with that fur on his head sticking straight up. Photographer Geert Weggen of Sweden is an expert at taking pictures of animals. When snow fell in October, he rounded up the neighborhood squirrels for their own winter games, using nuts as treats to “talk” them into it. Of course, Geert couldn’t give these furballs his own giant skis…he had to make squirrel-sized skis, poles, snowmobiles, and trophies, all of which uses math. Check out this page to see the squirrel’s skiing, sliding, snowy friends. Thank you to our fan John O. for finding these — and may the best squirrel win!

*Wee ones:* A squirrel’s back paw is only about as long as your pinky. Find 3 things in your room as small as that.

*Little kids:* If Geert fed a squirrel 3 nuts as a treat, then another 3 nuts, how many nuts did the squirrel get? *Bonus:* Posing the squirrels takes lots of time. If Geert took 4 full days to take the picture above and Tuesday was the 1st day, what day was the 4th?

*Big kids:* If a squirrel is 12 inches tall and you’re 4 times as tall, how tall are you? *Bonus:* If you wear 2-foot-long skis and the squirrel needs skis 1/4 as long as yours, how long do the squirrel’s skis need to be, in inches? (Reminder if needed: A foot has 12 inches.)

*The sky’s the limit:* If your skis are exactly your height in inches, and a squirrel needs skis 1/6 as long, will the squirrel’s skis be a round number of inches?

Answers:

*Wee ones:* Items might include erasers, pieces of crayons, marbles, or Lego bricks.

*Little kids:* 6 nuts. *Bonus:* Friday.

*Big kids:* 48 inches, since you’re 4 feet. *Bonus:* 6 inches, since you need half a foot (or 1/4 of 24 inches).

*The sky’s the limit:* Different for everyone…for your height to be divisible by 6, it needs to be an even number that’s also divisible by 3. The test for 3 is whether the digits of the number add up to a multiple of 3 themselves.

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]]>The post The World’s Fastest Animal appeared first on Bedtime Math.

]]>It’s a bummer we can’t fly the way birds do. The best we can do is jump out of a plane and fall at 120 miles per hour, until the parachute opens (hopefully). Even that isn’t anywhere nearly as fast as the peregrine falcon. This bird hunts animals for dinner by doing nosedives out of the sky at more than 200 miles an hour! That makes the peregrine falcon the fastest animal on Earth. The peregrine falcon has a third eyelid on each eye that helps keep its eyeballs moist in that speedy breeze. It also has bones on its beak push air to the side so the bird can breathe while diving. So nothing can stop this hunter!

*Wee ones:* If a falcon catches 6 pigeons for dinner, what numbers would it say to count them?

*Little kids:* Who’s faster, a falcon flying at 200 miles an hour, or a car driving at 100 miles an hour? *Bonus:* Who has more eyelids, 3 peregrine falcons, or you and 3 friends?

*Big kids:* If you skydive at 120 miles an hour, how much faster can the 200-mile-an-hour falcon fly? *Bonus:* The falcon’s strong wings can be up to 47 inches across. If you lay across that bird, how would your length compare to that?

Answers:

*Wee ones:* 1, 2, 3, 4, 5, 6.

*Little kids:* The falcon! *Bonus:* The falcons. Since everybody has 2 eyes, you can count just everyone’s left eye. The falcons’ left eyes together have 9 eyelids, while you and your friends have 8.

*Big kids:* 80 miles an hour faster. *Bonus:* Different for everyone…subtract your height in inches from 47, or vice versa.

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]]>The post How Long Will the Snow Stick? appeared first on Bedtime Math.

]]>We love, love, love it when lots of snow falls and we get a day off from school. Then we can go sledding, build snowmen, etc. But at some point, the snow melts away. Our fan Cadence asked, how long does that take? Well, it turns out there are 2 grown-up ways to use math to figure that out. One compares all the heat coming in and out: heat from the sun, heat from the ground below, and heat lost to the cold air. The other way compares the temperature that day and 32 degrees F, which is the freezing point. Every day is different, but as a rule of thumb, in 40-degree weather we lose half an inch of snow per day. 50-degree weather melts 2 to 4 inches a day! Let’s hope it stays cold for our sledding and snowmen.

*Wee ones:* A snowflake has 6 sides. Can you hold up 6 fingers?

*Little kids: *If there are 3 inches of snow on the ground and 1 inch melts today, how many inches are left tonight? *Bonus:* If it snows 1 inch each hour from 2:00 in the morning until 6:00 in the morning, how many inches of snow did you get?

*Big kids:** *If there are 10 inches of snow on the ground, how many more inches of snow need to fall for it to reach the top of your head? * Bonus: *If that snow melts away 2 inches every day, how many days until it’s all gone?

Answers:

*Wee ones:* Count to make sure you have 6 fingers up: 1, 2, 3, 4, 5, 6.

*Little kids:* 2 inches. *Bonus:* 4 inches, since it snows for 4 hours.

*Big kids:** *Different for everyone…find your height in inches, and subtract 10. *Bonus: *Again, different for everyone: take your height in inches of snow, and divide by 2 to find how many 2s need to melt away.

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]]>The post Calling All Cars! appeared first on Bedtime Math.

]]>On a busy road, the traffic can stretch for miles and miles. And that’s just one road in one town…imagine how many cars are on all the roads in your country! Our friend Abigail T. went even bigger: she asked us, how many cars do we have in the whole world? (and painted a picture of herself riding around in one!) Well, there are more than 1 *billion* cars out there (1,000,000,000). A million is a thousand thousands, and a billion is a thousand millions, so that’s a huge number. In the U.S. alone, there are 245 million cars for just 320 million people!

*Wee ones:* If you just count 4 blue cars on the road, what number do you say before 4?

*Little kids:* If 5 houses on your block each have a 2-car garage, how many cars can they hold together? Count up by 2s! *Bonus:* If on the road the 1st car in front of you is red, then the 4th car, then the 7th car…what’s the next red car to keep up the pattern?

*Big kids:* If people in your town bought 100 new cars this month, but 91 old cars went to the junkyard, how many more working cars are there now than a month ago? *Bonus:* If every U.S. car owner had 2 cars of those 240 million, how many people would have cars — and how many of the 320 million Americans would NOT have a car?

*The sky’s the limit:* There were 500 million cars in 1986, so it doubled by 2010. If it always takes the same amount of time to double, when will we have 4 billion cars?

Answers:

*Wee ones:* 3.

*Little kids:* 10 (2, 4, 6, 8, 10). *Bonus:* The 10th car, since every 3rd car is red.

*Big kids:* 9 more cars. *Bonus:* Only 120 million people would have a car, so 200 million would not.

*The sky’s the limit:* The year 2058. It took 24 years to double that 1st time. To reach 4 billion, we need to double from 1 to 2 billion, then from 2 to 4 billion. Each of those 2 jumps takes 24 years, for a total of 48 years after 2010.

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