This Week from Bedtime Math: Roll With It

What&s the longest object in your house? Do the math and find out. It might just be a roll of toilet paper!
By Laura Overdeck
Apr 23, 2013



Apr 23, 2013

Toilet paper is one of those things we don’t really think much about, except when it runs out. But toilet paper is actually a pretty interesting mathematical object. How long is a roll of toilet paper, anyway? How many times does the paper wrap around? When you take a closer look at a roll of Charmin or Scott, it turns out that that whole continuous sheet is one of the longest objects in your house and yet it all fits onto one little tube.

What’s even cooler is how it’s made. The paper is rolled onto a tube that’s over 5 feet long, then chopped into little rolls. Good thing, otherwise you’d need a much bigger bathroom.

Wee ones (counting on fingers): If you have a pack of 6 toilet paper rolls, and you and your friend roll 2 of them down the hall to see whose will roll farther, how many rolls do you have left?

Little kids: If each long tube of toilet paper at the factory gets sliced into 16 rolls, how many 4-packs can you make from one long tube? Bonus: If you’re stacking rolls of toilet paper to build a fort and each wall uses 20 rolls, how many rolls do you need for 4 walls?

Big kids: Say you have a roll of toilet paper with 240 square sheets and each sheet is 4 inches long. How long is the whole roll if you unroll it, in feet? (Hint: 4 inches is a nice neat fraction of 12 inches) Bonus: If you unroll it down the 62-foot hallway in your school, how much toilet paper will you have left to turn around and roll it back the other way, in feet?

A message from Laura: Bedtime Math is a simple idea: we all know we should read to our kids at night, but what about math? My husband and I have done fun, mischief-loaded math problems with our kids at night for years. When at age 2, our third child started hollering for his own math problem, we realized we were onto something:  In a world where so many people say “Ewww, math!”, we had created a household culture where kids don’t just tolerate math, they actually seek it out.   Now we email parents a fun, lively math problem every day to do with their kids – and every week, we’ll be posting a new problem right here on Scholastic Parents!  Check out this week’s problem below ~

Wee ones: 4 rolls left.

Little kids: 4 4-packs. Bonus: 80 rolls.

Big kids: 80 feet! (or 960 inches). Bonus: 18 feet left.

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