The Roll of a Lifetime

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.

The Roll of a Lifetime

April 9, 2019

You probably don’t think about toilet paper too often – until it runs out. Well, if you get the new ‘Forever Roll’ of toilet paper, you’ll think about it even less! This giant roll weighs 2 pounds and is 9 inches in diameter (distance across that circle). It’s so enormous that it needs its own special holder. There are 1,700 squares of TP, which add up to 555 feet of paper. If you unrolled the whole thing, that length would stretch farther than 12 school buses, and would match the height of the Washington Monument! Despite all that, it won’t really last forever like the name says – but at least when you need a refill, you can roll it right home from the store. 

Wee ones: How many rolls of toilet paper do you see in the picture?

Little kids: How many 2-pound rolls of toilet paper add up to 10 pounds of paper? Count up by 2s if it helps! Bonus: If normal toilet paper rolls are 5 inches across, which is wider, 2 of those next to each other, or the 9-inch Forever Roll?

Big kids: If a normal roll of toilet paper weighs 1/4 pound, how many normal rolls together weigh the same as the 2-pound Forever Roll? Bonus: If you use the bathroom 4 times a day using 3 squares each time, and you start a new roll first thing on Sunday morning, on what day of the week will you use the 100th square?

The sky’s the limit: Normal toilet paper squares are about 4 inches long. If those 1,700 squares were exactly 4-inch squares, would the roll be longer or shorter than the 555-foot Washington Monument? See if you can figure out a shortcut to solve this!

Answers:

Wee ones: 3 rolls.

Little kids: 5 rolls, because 2 + 2 + 2 + 2 + 2 = 10. Bonus: The 2 small rolls, because they total 5+5=10 inches across, which is greater than 9.

Big kids: 8 rolls, because 4 rolls weigh 1 pound and you need 2 sets of that to make 2 pounds. Bonus: On the Monday a week later. You use 12 squares a day, and the biggest multiple of 12 less than 100 is 96 (= 8 days of usage). The 8th full day is the following Sunday, since Saturday is the 7th, so you’ll use the remaining 4 squares on Monday.

The sky’s the limit: The roll would be longer, at 566 ⅔ feet. Each 4-inch square is exactly 1/3 foot. So you can just divide the number of squares by 3 to figure out how many sets of 3 there are in that 1700. Multiples of 3 have digits that add up to a multiple of 3, so the closest smaller number that’s divisible by 3 is 1698, giving us 566 plus a leftover 2 squares. The longer way is to multiply the 1700 squares by 4 inches each (to get 6800), then divide that by 12, but why do all that extra work? :)

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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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