The Mental Math Quiz

EDUCATION

Talin Vartanian

5 Min Quiz

Image: JGI/Tom Grill / Blend Images / Getty Images

About This Quiz

This quiz will take a look at 35 math-related questions that involve various mathematical concepts. Some of these include word problems, addition, subtraction, exponents, square roots and cubed numbers.

Percentages are also involved in this quiz. For example, do you know what 20% of 20 is? An easier way to look at this is 10% of 20, which is 2. When you take 10% of a number, you're just removing that 0 from the end. So when you take away 0 from the end of 20, you get 2, which is 10% of 20. Now to find out what 20% of 20 is, just double that 2 number to get 4. Thus, 20% of 20 is 4.

We'll also take a look at some exponents in this quiz. For instance, do you know what 3³ is? One way to look at this problem is like this: 3(3)(3), which is 27. To cube a number means to multiply that number three times. This is also similar to squaring a number, which is done with the symbol: ². To square a number means to take a number and multiply it by itself. For example, 2² is 4, since 2(2) is 4.

Now that the warm-up is done, it's time to sharpen your math skills with this mental math quiz!

Do you know what the square root of 144 is?

The square root of 144 is 12. In other words, 12 times 12 is 144.

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What is 6 multiplied by 8?

When you multiply 6 by 8, you get 48. This is an even number.

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What is 50 divided by 2?

The answer is 25. In other words, if you multiply 2 by 25, you get 50.

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Can you guess what the cube root of 27 is?

The answer is 3. The cube root of 27 means that 3(3)(3) = 27.

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Do you think you know what 10² is?

10² is 100. In other words, 10 times 10 is 100.

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Do you know what 2³ is?

8 is the correct answer. To cube a number means to multiply it three times. Since 2(2)(2) = 8, the number 2 cubed is 8.

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What is 27 + 19?

46 is the right answer. An easier way to look at this is 27 + 20 is 47, minus 1 is 46.

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Try and guess what 52 - 23 is!

29 is the right answer. Sometimes it's easier to round one of the numbers in the question to make the computation easier. For instance, instead of trying to calculate 52 - 23, try 50 - 23, which is easier to compute to 27, then add 2, which is 29.

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What is 0 divided by 1?

The right answer is 0. 0 divided by any number is still 0.

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What is 2 divided by 0?

The answer cannot be computed. You can't take a number and divide it by 0.

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Can you guess what -1 + 1 equals?

The correct answer is 0. Another way to look at the question is 1 - 1, which is 0.

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What is -20 divided by -2?

10 is the right answer. When you divide two negative numbers, the answer is a positive number. So, -20 divided by -2 equals 10.

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What is -4 multiplied by 9?

-36 is the correct answer. When you multiply a positive and a negative number together, the answer is a negative number. So, -4 multiplied by 9 is -36.

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Do you think you know what -2 - (-9) is?

7 is the correct answer. When you are subtracting these two negative numbers, another way to look at it is -2 + 9, which means the same thing as -2 - (-9). So, -2 + 9 is 7, since you're subtracting 2 from 9.

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Try and guess what (-10 +2)/2 is!

-4 is the right answer. Let's walk through this problem: -10 + 2 is -8, because you're taking away 2 from -10. Now you take -8 and divide it by 2, which is -4.

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What is (2 + 1)/(0 + 1)?

3 is the right answer. Let's walk through this problem, starting with the numerator: 2 + 1 is 3. The denominator, 0 + 1 is 1. Now you take 3 and divide it by 1, which is 3.

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What is (2 -1)³?

1 is the right answer. Do the problem in parentheses first, so 2-1 is 1. Now the problem is 1³, which is just 1.

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What is the square root of 0?

The square root of 0 is still 0. In other words, 0 times 0 is still 0.

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Do you know what the square root of -1 is?

i is the correct answer. i means "imaginary number" in math terms. Don't worry if you didn't get this one right - it's complicated!

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Try and guess what (-2)² is!

(-2)² is 4. Another way to look at this problem is like this: -2 times -2 is 4, since two negative numbers become a positive number.

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Think you can figure out what 20% of 50 is?

The answer is 10. Let's work this problem out: 10% of 50 would be 5 (just take that 0 away from the end). Now just double the 5 to get 10, which is 20% of 50.

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What is 5% of 10?

.5 is the answer. If we know that 10% of 10 is 1 (you just take that 0 away from the end of 10, leaving 1), then we can just halve that 1 to .5, since we want to know what 5% of 10 is.

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Can you figure out what 4² + 3² is?

25 is the correct answer. 4² is 16, since 4 times 4 is 16. And 3² is 9, since 3 times 3 is 9. So, 16 + 9 is 25.

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What is 3³ + 1³?

The right answer is 28. 3³ is 27, since 3(3)(3) is 27. 1³ is still 1, since 1(1)(1) is 1. So, 27 + 1 is 28!

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Can you guess what 1,256,498 divided by 1 is?

The answer is 1,256,498, since ANY number divided by 1 is still the same number. 2 divided by 1 is still 2, 500 divided by 1 is still 500, and so on.

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Sally has two apples, three oranges and one kiwi. If I take two oranges away from her, how many pieces of fruit does she have now?

4 is the right answer. Sally has a total of six fruits in the beginning. If I take two oranges from her, now she has four pieces of fruit.

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An item at a store costs $2.10. If I give the cashier a $5 bill, how much change can I expect back?

$2.90 is the right answer. In other words, 5 - 2.1 is 2.9.

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An item at a store costs $20, but I have a coupon for 10% off. How much does the item cost now?

The item now costs $18. Here's why: 10% of $20 is $2 (you just remove that 0 from the end of 20 to get 2). Now, you just subtract $2 from $20, which leaves $18.

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It's 9:00 now. What time will it be 3 hours and 14 minutes from now?

The answer is 12:14. If it's 9:00 now, in 3 hours it will be 12:00, since 9 + 3 = 12. Since we know it's 12:00, we just add 14 to get 12:14. Doesn't matter if we're near noon or midnight.

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It's 3:30 now. What time was it one hour and 28 minutes ago?

2:02 is the right answer. If it's 3:30 now, one hour ago it was 2:30. Now we just take 28 minutes from 30 minutes, which leaves 2 minutes. Thus, the answer is 2:02.

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Try and solve this problem: (2+2)² - (1-1)³

16 is the right answer. (2+2) is 4, and 4² is 16. (1-1) is 0, and 0³ is still 0. So, 16 - 0 is 16.

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What is (√100)²?

100 is the correct answer. The "√" and the "²" cancel each other out in this problem. Here's another way to look at this: the square root of 100 is 10. 10², or 10 times 10, is 100.

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What is √25 + √16?

9 is the right answer. The square root of 25 is 5. The square root of 16 is 4. 5 + 4 is 9.

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What is 7 times 7?

7 times 7 is 49. Another way to look at this is 7², which is 49.

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What is the answer to this problem: (2³)/(2²)?

2 is the right answer. 2³ is 8, since 2(2)(2) is 8. 2 squared is 4, since 2(2) is 4. 8 divided by 4 is 2.

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