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Halloween Math and More Percentage Questions

What's 17% of 200? How do you calculate the original price of something before a 30% markup? What math makes the Halloween holiday go round-and-round? Keep on reading to learn the answers to these and more frequently asked questions about percentages!

By
Jason Marshall, PhD,
Episode #172

Halloween MathBoo!

Yes, it's that time of year when the air starts feeling chilly, leaves start falling, pumpkins and faux cobwebs adorn porches, and math fans of the world start thinking about the spine-tingling mathematical fun facts that make the Halloween holiday tick.

As we'll soon discover, some of the spookiest Halloween fun facts are about percentages - which gives us the perfect opportunity to follow up on our previous episode of frequently asked questions about percentages with a few additional percentage-themed questions sent to me by math fans everywhere.

So, without further ado, let's get started!.

Halloween Math

When you think of Halloween, do you think of math? If you're like 99.9% of the population (a statistic which I totally made up), the answer is a resounding "No!" You probably think about the pumpkin you need to carve, the costume you need to make, and—of course—the candy you need to scarf down.

While those are totally reasonable Halloween concerns, it turns out that there are some really interesting numbers associated with this holiday, too. For example, the History Channel has a great infographic called Halloween by the Numbers containing lots of answers to questions like:

  • What percentage of Americans dress up their pets for Halloween?
  • What percentage of adult Americans hand out candy?
  • What percent of parents admit to sneaking candy out of their kids' trick-or-treat bags?

Before I reveal the percentages that answer these questions, let's take a few minutes to answer a few of your fellow math fans' frequently asked questions about percentages.

FAQ: "How Do You Find What 200 Is 17% Of?"

"Math Challenged Gal" writes:

"This is a math problem I have to calculate on a regular basis in my life: "200 is 17% of what?" Or "1,020 is 17% of what?" Or "850 is 17% of what?" The first number changes from time to time. What is a simple way to figure this out so that I can always find the answer no matter what that number is?"

Frequently Asked QuestionsTo get started with problems like this, it's useful to employ a bit of algebraic thinking. By which I mean: let's assign a variable—we'll call it x—to the unknown value that so far has been called "what" in problems like "200 is 17% of what?" Why do we do that? Because it allows us to state this problem in a way that's much easier to work with—as an equation.

Instead of "200 is 17% of what?" think of this problem as asking: "200 is equal to 17% of a number x. What is x?" If you think about it, you'll see that this is the same as the equation: 0.17 * = 200, which we can solve by dividing both sides by 0.17.

This gives us x = 200 / 0.17 or approximately 1,176. So 200 is approximately 17% of 1,176. If the number 200 changes to 1,020, we can simply insert that new value into the equation. Doing so tells us that 1,020 is 17% of 6,000 (which is 1,020 / 0.17). That's all there is to it!

FAQ: "What's the Price Before a 30% Markup?"

Math fan Barbara writes:

"I have a product which is selling for $12.30. If the markup is 30%, how can I quickly find the original price?"

This is another case where a bit of algebra comes in handy. If we call the original price (the one we're trying to find in the problem) x, then we can turn this question into the equation: 1.3 * x = $12.30. Why 1.3? Because the fact that an item is marked up 30% means that its retail price is actually 130% of its wholesale cost. So this equation is asking: "What number times 1.3 is equal to $12.30?"

We can find that number by dividing both sides by 1.3, which tells us that the original cost of the item is $12.30 / 1.3 or approximately $9.45.

Halloween by the Numbers

And with that, we've arrived at the part of the show that you've all been eagerly waiting for—the big reveal of the answers to the Halloween fun fact questions from the History Channel's infographic that I mentioned earlier.

Up first, it turns out that 11.5% of Americans dress up their pets for Halloween. Do you? If so, and in particular if you can come up with a good mathematically themed costume for your little buddy, please take a picture and share it with your fellow math fans on the Math Dude's Facebook page.

As for the percentage of American adults who hand out candy, a whopping 72% of adults participate in this tradition.

And finally, the percentage of adults who admit to sneaking candy out of their kids' trick-or-treat bags is…90%!

If you've enjoyed these fun facts, I encourage you to check out the full History Channel infographic for more.

Wrap Up

Okay, that's all the math we have time for today. Be sure to check out my mental math audiobook called The Math Dude’s 5 Tips to Mastering Mental MathAnd for even more math goodness, check out my book The Math Dude’s Quick and Dirty Guide to Algebra.

Remember to become a fan of the Math Dude on Facebook where you’ll find lots of great math posted throughout the week. If you’re on Twitter, please follow me there, too. Finally, please send your math questions my way via FacebookTwitter, or email at mathdude@quickanddirtytips.com.

Until next time, this is Jason Marshall with The Math Dude’s Quick and Dirty Tips to Make Math Easier. Thanks for reading, math fans!

Halloween math and FAQ graphics from Shutterstock.

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