Can You Ace This Mental Math Quiz?


By: Robin Tyler

6 Min Quiz

Image: gremlin/E+/Getty Images

About This Quiz

Do you love adding up license plate registration numbers while you're driving? Do you see numbers during your daily routine and immediately start to add or subtract them?

Well, you are not alone! There are many people that love to do mental math whenever they see a set of numbers. They might add them, subtract them, multiply or divide them! Just as long as they test their brain's ability to do math.

So if you are like that, you are going to love this mental math test where all you have is your gray matter. No calculators allowed here! That trusty brain will help you to remember high-school math!

And this quiz is going to push you, that is for sure! Addition, subtraction, logical math reasoning, division, multiplication. They are all represented. Oh, and there are a few surprises thrown in, just for a little extra fun. 

You have all the time you need to work your way through 35 mental math questions, each one pushing you, the prime mathlete, to the limit. So make sure you go where no mathlete has ever gone before!  

Of course, if you don't know the answer, you could make use of our helpful hints, just to nudge you in the right direction!

So what are you waiting for, champ? Let's get this done!


What is 35+75?

It's easiest to work out if you break it down. First, round down the numbers. So round 75 down to 70 and 35 down to 30. It is easy to see that those two equal 100. Then you still have 5 and 5 to add. And that gets you to 110!


Divide 100 by 20. What is your answer?

This is relatively simple division. Again, it's easiest when you break it down. So drop some zeros and you can just divide 10 by 2. That leaves you with 5. So if you scale it up, that 100 divided by 20 is also 5.


If you subtract 33 from 101, what are you left with?

This one is easiest if you break it down. Break 101 down into 10 and 1. And break 33 down into 3 and 3. Then take 10 minus 3, which leaves you with 7. Now the tricky bit. 1 minus 3 won't work, but 11 minus 3 is 8. Take one away from the 10 minus 3 to cover the carryover, and you are left with 68.


When you multiply 25 by 9, what do you get?

Although it seems a difficult answer to work out in your head, it's not that bad. Always look at what you have before you. In this case, we know that 25 multiplied by 10 would give us 250. But because we are multiplying by 9, we must take off 25 from 250. That leaves us with the answer of 225.


If an apple cost 5 cents, a pear 3 cents and a banana 1 cent, how much would you have spent on two apples, a pear and three bananas?

Oh, how some people hate math problems like this. Just break it down logically and it is easy. Sometimes writing it down helps. An apple is 5 cents and we have two. That makes 10 cents altogether. A pear is 3 cents, we have 1, so that is 3 cents. Finally, a banana is 1 cent and we have three, so that is another 3 cents. Now simply add 10 and 3 and 3, and we have the answer... 16 cents.


If a man walks 50 miles to the east, and then 30 miles to the west, how far has he walked?

Did we trick you? No? Well, it is amazing how some people fall for math questions like this. If he walked 50 miles one way and then 30 miles back in the exact opposite direction, he still walked 80 miles in total. Some people think 20 miles, because that is how far he is from his original starting point. It's simply a case of not reading the question properly.


Can you tell us the square root of 36?

To determine the square root, you must find the number that is multiplied by itself to get the final total - 36 in this case. Basic multiplication tables tell us that the number is 6, as 6 multiplied by 6 is 36.


Add 22+47 and what do you get?

Simple addition: it's 69. We got there by adding 2 and 4 to get 6, and then 2 and 7 to get 9, therefore 69.



You will notice similar numbers, such as two 999s and two 300s. Look closely and you will see that they cancel each other out. So, effectively, the sum is 1,000 plus 1, and we all can work that out! 1,001.


If you had 35 oranges and you lose 18, how many oranges do you have?

This is simple subtraction. 35 minus 18 is 17. And you need to take better care of those oranges, please.


A ream of paper has 400 sheets. A box has 5 reams in it. How many sheets of paper are in 4 boxes?

Let's approach it step by step. We know a ream is 400 sheets. There are 5 in a box, so each box has 2,000 sheets. And we have 4 boxes, so that is 2,000 multiplied by 4, which is 8,000. Easy, right?



Although it looks difficult to do without a calculator, it really isn't. Just break it down. Starting from the back, 101 plus 99 is 200. Also, 77 and 33 is 110. Add them together and you get 310.


If 16 km is the equivalent of 10 miles, how much is 64 km?

Don't let the words confuse you - this is simple math. To go from 16 to 64 kilometers, you multiply by four. So to get the answer in miles, you do the same. And it is 40!


What is 20x40 equal to?

Break it down and take 4x2, and you have 8. It's just 100 times that, as it is 40x20. So the answer is 800.


What is 5% of 150?

The answer is 7.5. How do we get that? 10% of 150 would be 15. Seeing that 5% is half of 10%, we must halve 15 to get the answer, which is 7.5.



Ok, the easiest way to approach this is by rounding 332 up to 333. If you multiply that by 3, it's easy to see it would be 999. Then take off 3 from the rounding up. Simple when you know a few shortcuts, right?


x+400-25=385. What value is x?

Ah, the dreaded solve for x equation. Start with what you know, which is 400-25. That is 375. The final answer of the equation is 385, so logically, that means x is equal to 10. It's pretty easy when you break it down like that, right?



Let's break it down. 25x10 would give you 250, but you need to add another 25, as you were actually multiplying by 11.


Is 3 a prime number?

Prime numbers can only be divided by 1 and themselves. Can 3 be divided by 1? Yes, it can. Can it be divided by itself? Yes, it can. Can any other number divide into it to form a whole number? No. Therefore, 3 is a prime number.



It's not difficult to see that the answer to this question is 154. But let's break it down. The easiest way is rounding up the 99 to 100, adding 55, and then dropping the 1 from rounding up. That leaves you with 154.



8 minus 5 is 3, and 7 minus 3 is 4. That leaves you with 34 as your answer. Did you use the same method to work it out as we did?


What is the result of 15x0?

In math, you learn fairly early that anything multiplied by zero is zero. So that rule stands with this question. The answer is 0!


Which number am I? I am found in the range between 20 and 30 and I am a multiple of both 3 and 4.

Easy, it's 24. Why? Because 24 can be divided by both 3 (8 times) and 4 (6 times), and it falls into the range of 20 to 30 as stated in the question. If this still isn't clear, consider that the multiples of 3 between 20 and 30 are 21, 24 and 27; the multiples of 4 in that range are 24 and 28. The only number common to both lists is 24.


If you have 62 bananas and your girlfriend eats 44 of them, how many do you have left?

Well, other than the fact that your girlfriend might suffer from stomach cramps, you would only have 18 bananas left. We got to the answer by taking 62 and subtracting 40 to get to 22, and then taking off the remaining 4 to get to 18.


x is equal to 6. What is (4+x)(2+x)?

So let's find out the answers to the brackets first. That is fairly straightforward. (4+6) is 10, and (2+6) is 8. Therefore, our equation is 10x8, which we all know from our multiplication tables is 80.


To stay in a hotel costs $50 per night. You stay for four nights and check out on the fifth morning. How much will you pay?

You will only pay for the nights you slept over, so $200 in total for four nights. You had to be out of the room on the fifth morning, so you were not charged for that. Beware: there might be additional charges like room service or certain taxes as well.



It's easy when you do it in bite-sized chunks. 999-33 is 966. 966-87 is 879, and then subtract the final 100 to get 779.


A doctor tells you to take a pill every quarter of an hour, so how many would you have taken between 10 a.m. and 12:01 p.m.?

You would take 9 tablets in total. Let's break it down. You would take one at 10 a.m., 10:15 a.m., 10:30 a.m., 10:45 a.m., 11 a.m., 11:15 a.m., 11:30 a.m., 11:45 a.m. and 12 p.m.


5 to the power of 2 is equal to what?

5 to the power of 2 is essentially a fancy way of saying 5 squared, or 5 multiplied by itself. All those fancy words just to get an answer of 25. We will multiply rather!



As we know, anything multiplied by zero is zero. Therefore 6x0 is zero, and zero added to 78 is still 78. Get it? Of course you do!


What is 10% of $121?

To find the answer to this question, we can simply divide by 10. That leaves us with $12.10 as the answer. To cross check, multiply that by 10 to get back to $121.


Tell us the answer to 65x3x0, please?

Anything times zero is zero! The answer is 0. This is a very basic rule of math, taught to students at an early age. Did you remember it?


Calculate 57+60+10-57.

The answer is 70, and it's easy to get to. Look at the whole sum. If you look closely, the two 57s cancel each other out, leaving 60 plus 10!



Simple. Break it down like this. 9-7 is 2, and again 9-7 is 2, so 22. When you split math into steps, it certainly becomes a lot easier, right?


Tell us the answer to 550÷11, please?

Simple really, because 550÷11 is 50. Why? Well, 550 divided by 10 would be 55, so divided by 11 it's 50.


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