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13 Grade School Math Problems Most Parents Can't Solve

Are you smarter than a fifth grader? No, we're not offering a cash prize if you can prove it. But after struggling with these "easy" math questions we'd like to see how many you can solve.

We promise you don't need a calculator for any questions, but keep a pencil and paper handy because the answers are on the last page!

1. Let's start simple

A study in Japan found that 60% of people in their 20s got this question right, compared to 90% of older generations. We're not sure what being a millennial has to do with math, but see if you can solve this equation.

Mind Your Decisions

2. What's the ?

The aim of this puzzle is to solve what number is in the ? space. Yes, it's really that simple. And no, we can't give you any other clues.

3. The bat and the ball

easyWallz

This is an oldie but a goodie:

A baseball bat with a ball costs $1.10. The bat cost $1 more than the ball. How much does the ball cost?

4. Let's Make a Deal

Damn Interesting

You're competing on a game show where there are three doors. One door is hiding $1 million, the other doors are empty.

You pick door #1. The host opens door #3 and reveals that it is empty. He asks you if you want to keep door #1 or switch to door #2.

Which is the best answer?

5. Here's a head-scratcher

Take a look at this equation and see if you can solve it:

What's the answer?

6. Lily pad logic

TES.com

There's a lake with a patch of lily pads growing on it. Every day, the patch doubles in size. If it takes 48 days to cover the whole lake, how long would it take to cover just half of the lake?

If those aren't tough enough we have more questions, and of course the answers are on the last page.

7. The penny question

Two Pennies / Twitter

Which is better? Being given $10 million right now, or getting a penny today, two pennies tomorrow, four pennies the next day and so on for a month?

8. Mental math

Don't use a calculator or pencil for this question, do all the math in your head.

Now write down your answer.

9. Solve the equation

10. This one is tricky

They say that a six-year-old can solve this in just 20 seconds. It takes some adults a lot longer.

11. This one could drive you insane

12. The missing dollar

Read this story about a boy buying a shirt and see if you can make heads or tails of it:

13. Parents hated this homework question

Can you see where they all went wrong trying to solve it?

Turn to the next page for the answers - if you're brave enough!

Answers

Question 1: 1 (You should divide the 3 by 1/3 first to get this answer).

Question 2: 6 (All the rows and columns in the puzzle add up to 15).

Question 3: 5 cents (People assume the ball must cost 10 cents, but if that was true that bat would be $1, and only 90 cents more expensive).

Question 4: You should switch. When you picked a door your odds were 1/3. With door #3 removed, your odds are now 1/2. BUT you were more likely to pick an empty door first, so switching is the better option. If you're still confused you can watch a video to see a longer explanation.

Question 5: 9. After doing the brackets and exponents, remember to work from left to right. The problem goes like this: 6÷2(1+2) equals 6÷2*(1+2), which is the same as 6÷2*3 or 3*3 = 9.

Question 6: 47 (If the patch doubles in size every day, on day 47 it's half as big as day 48, and covers half the lake).

Question 7: The pennies are the better choice. By the end of the month, they'll have doubled and doubled to make $10,737,418.23. Really! These guys did the math for you.

Question 8: 4,100. By the end of the problem, you get so used to adding without "carrying over" that you probably jumped from 4,090 to 5,000. Oops!

Question 9: 2. The equation is just the last line, the first two are unrelated. Sorry, that one was a little mean!

Question 10: It's parking space 87. Try looking at the problem upside down.

Question 11:14. Look closely at the last line: bananas are worth one each and coconuts are worth one each. As you can see, there's just one coconut and three bananas in the final question.

Question 12: There was no missing dollar. The boy makes the mistake at the end of the story when he adds up the two $49 debts ($98) and then adds his $1. He should subtract his $1 instead, to end up at $97, the price of the shirt.

Question 13: 65. Try working backwards, that makes the question much easier.

How many did you get right?

I write about all sorts of things for Shared, especially weird facts, celebrity news, and viral stories. CONTACT: zachary@shared.com