Double Bubble Trouble

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.

Double Bubble Trouble

February 9, 2016

Soap isn’t what it used to be. In the old days, soap always came in a bar or block; when kids said naughty things, their parents would shove soap in their mouths to “wash” them out. These days, soap can also squirt from a bottle. So our friends Mihira and Siona T. asked, how many gallons are in the world’s largest bottle of liquid soap? (with a great drawing to give us the idea). Well, the Guinness world record-holding bottle held a special kind of liquid soap: shampoo. The 19-foot 5-inch tall shampoo bottle stood in a mall in Jeddah, Saudi Arabia, and held 6 tons of shampoo, which is 12,000 pounds. Like water, shampoo weighs about 8 pounds per gallon…if we carve that all up into 8-pound chunks, we get 1,500 gallons! If you sudsed up all that shampoo at once, you might beat the record for the world’s biggest soap bubble ever, which took up 3,400 feet. At that point, that bubble could wash your whole house!

Wee ones: What shape are bubbles floating through the air?

Little kids: If you shampoo your hair the 1st day, then shampoo your dog the 2nd day, then yourself the next day, then your dog, and so on…who gets a shampoo on the 8th day?  Bonus: If you start with your own shampoo on a Monday, on what day does your dog get his 3rd shampoo?

Big kids: If you and your friends are each 5 feet tall, how many of you would have to stack head to toe to stand at least as tall as the 19-foot 5-inch bottle?  Bonus: If each gallon of shampoo can suds up 100 people’s hair, how many people can that 1,500-gallon bottle shampoo?

The sky’s the limit: Just to compare, a bathtub holds about 50 gallons if filled to the top. If there are 20 houses on your street block and each has 1 bathtub, could you fill everyone’s tub with shampoo from that 1,500-gallon bottle?




Wee ones: Balls, or “spheres” (and from the side, they look like circles).

Little kids: Your dog.  Bonus: On Saturday.

Big kids: 4 of you (20 feet), since 3 of you reach only 15 feet.  Bonus: 150,000 (150 thousand)!

The sky’s the limit: Yes! The bottle can fill 1,500 divided by 50 tubs, or 30 tubs.

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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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