If You Can Get Every One of These Mental Math Problems, Your IQ May Be in the 99th Percentile


By: Robin Tyler

6 Min Quiz

Image: Ariel Skelley/DigitalVision/Getty Images

About This Quiz

Ok, first things first. That calculator on the side of your desk... put it away. Lock it in a drawer if you have to. 

This is a mental math test and you, yes you, are going to get through it using just your brain! That old gray matter that remembers every bit of math from high school. Yes, it is there somewhere. Compartmentalized, locked away, just waiting to spring into action to help you through this tough quiz.

And believe us when we say that this mental math test will push you to the limit. Addition, subtraction, logical math reasoning, division, multiplication. You are going to have to be on your toes if you want to ace this one. 

But don't worry, you have all the time you need to go through 35 questions, each one pushing you, the prime mathlete, to the limit. Go where no mathlete has ever gone before! Aim for the 99th percentile. You can do it!

And if you are truly stuck and don't know the answer, our little helpful hint will just push you in the right direction!

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

Good luck! Ready, steady, MATH! 

What is 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 that number is 6, as 6 multiplied by 6 is 36.


x+300-25=285. What value is x?

The easiest way to deal with a solve for x equation like this is to start with 300-25. That is 275. The final answer of the equation is 285, so logically, that means x is equal to 10. It's pretty easy when you break it down like that, right?



Division of round numbers with even digits is fairly simple. As with many math problems, the more you can break it down, the better. So drop the zeros and divide 12 by 3. The answer is 4. Two zeros cancel out each other, leaving one remaining. Add that to the 4, and you have your answer: 40!



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


What is 10% of $123?

To find the answer to this question, we can simply divide by 10. That leaves us with $12.30 as the answer. To cross check, multiply that by 10 to get back to $123.


A ream of paper has 400 sheets. A box has 6 reams in it. How many sheets of paper in 3 boxes?

Oh I love these. Let's approach it step by step. We know a ream is 400 sheets. There are 6 in a box, so each box has 2,400 sheets. And we have 3 boxes, so that is 2,400, multiplied by 3 is 7,200. But you knew that, right!


What is 323+444?

Breaking it down, add the first numbers, second numbers and then third numbers. So 3 plus 4 (7), 2 plus 4 (6) and 3 plus 4 (7). Your answer is 767.


x is equal to 7. What is (4+x)(2+x)?

So let's find out the answer to the brackets first. That is fairly straightforward. (4+7) is 11. And (2+7) is 9. So therefore, our equation is 11x9, which we all know from our multiplication tables is 99.


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!



You will notice similar numbers, such as two 999's and two 300's. 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.


3 to the power of 3 is equal to what?

3 to the power of 3 is essentially a fancy way of saying 3 multiplied by 3. The answer is 9.


Subtract 112 from 777, and what do you have?

Let's do it this way. 7 minus 1 is 6. 7 minus 1 is 6 and then 7 minus 2 is 5. So it's 665. Easy, right?


500=250+27-32+x. Solve for x?

The correct answer is 255. Start with 500, then subtract 250, subtract 27 and add 32.



The right answer is 233. See, 233x4 is 932. You could also break it down as follows. Four divides into 9 twice (2), carry the remaining 1 over and add to 3. Four divides into 13 three times (3), carry the remaining 1 over and add it to 2. Four divides into 12 three times (3). So your answer is 233.


Tell us the value of x, if 25-x=-5?

To answer this, ask yourself, if I have 25 and I need -5, what number takes me there? It is easy to see that number is 30.


8 is the square root of which of these below?

We know that the square root of a number is a certain number multiplied by itself. So if we look at 64, basic multiplication tells us that 8 multiplied by 8 is 64. And that is your answer!


There are 50 cookies in a box. How many in 5 and a half boxes?

Well, how much would half a box be? 25, that's right! Five boxes of 50 would be 250 cookies, easy enough multiplication. Then just add the 25 for the half-box and you have your answer, which is 275.



Ok, we know that 15 times zero is zero. So then you just have to multiply 83 times 2 for an answer of 166.


Can you solve this equation? y is equal to 3. What is (9+y)(12÷y)?

Starting with the brackets, we see that (9+3) is 12. And (12÷3) is 4. Now we just multiply 12 by 4 to get the answer. And that is 48. Taking simple steps towards the answer is the best approach.


Your favorite cereal, normally a 500g box, now has 20% more for free. How much cereal is in the box now?

10% more of 500g would be another 50g. So 20% is logically 100g, and if you add that to 500g you have 600g of cereal. Easy enough, right? I hope you got it!


Solve for y: 300-30+70+y=392

Start with the knowledge you have. You know that the answer to the equation is 392. Look at what else you have. 300 minus 30 is 270, add 70 and you have 340. Now subtract 392 from 340 to get y. There, y equals 52. Math is about doing things step by step!


How many meters less is 1.6 kilometers, compared to 2.1 kilometers?

This is not too difficult to work out. We know what there are 1,000m in a kilometer. So in 2.1 kilometers there are 2,100m and in 1.6 kilometers there are 1,600m. So subtract 2,100-1,600 to get your answer. And it is 500m. Easy enough, right?


A man is told to take a pill every quarter hour, starting at 11 a.m. How many pills would he have taken by 1:01 p.m.?

To find this answer easily enough, just break it down. So he takes his first pill at 11 a.m., second at 11:15 a.m., third at 11:30 a.m., fourth at 11:45 a.m., 5th at 12:00 p.m., sixth at 12:15 p.m., seventh at 12:30 p.m., eighth at 12:45 p.m. and ninth at 1:00 p.m. So nine in total. Hope you got it, because many people would say eight when working it out.


Can you tell us the square root of 49?

To determine the square root, you must find the number that is multiplied by itself to get the final total, 49 in this case. Basic multiplication tables tell us that the number is 7, as 7 multiplied by 7 is 49.


What is (8x5)-(12÷3)?

As you know, immediately on seeing this, you need to break it up into two separate parts. So 8 multiplied by 5 is 40, and 12 divided by 3 is 4. Then you subtract the 4 from the 40 to get your answer, which is 36.


A triangle has two angles of 70 degrees and 90 degrees. What would the third and final angle size be?

A triangle's internal degrees always add up to 180. So we know we have 90 and 70 degrees, which are equal to 160 degrees. So, to find the final angle, subtract 160 degrees from 180 degrees and you're left with 20 degrees for the final angle. And that's your answer! Simple enough!


What is 1,000÷25?

You got that, right? A simple division problem. Start by breaking it down into smaller numbers. We know that 100 divided by 25 is 4. So logically, 1,000 divided by 25 would be 40 (ten times more, as 1,000 is ten times more than 100).


What is 5% of $180?

This is easy enough. We know that 10% of $180 is $18, so to get 5% we have to halve that. Your answer is therefore $9.


If x=5, what is (2+x)(8-x)?

So let's find out the answer to the brackets first. That is fairly straightforward. (2+5) is 7. And (8-5) is 3. So therefore, our equation is 7x3, which we all know from our multiplication tables is 21.


Solve for x, if x-300+250+250=450.

Let's start with the known information. We have 250 plus 250 minus 300. So that leaves us with 200. The answer is 450, so subtract 200 from 450 to find out the value of x, which is 250.


What is 30% of 80?

Breaking it down into smaller chunks helps us find the answer easier. 10% of 80 is 8, so therefore 30% is 8x3, which is 24. No sweat!


If you divide 32 by 7, what remainder is left?

In math, a remainder is the part left over when completing an equation. In this case, 32 divided by 7 sees a remainder of 4. Why? Well, 7 goes into 32 four times (7 times 4 is 28), and 32-28 is 4 or the remainder.


Divide 50 by 20. What is your answer?

Drop the zeros to make it easier. We know that 5 divided by 2 is 2.5, and that too is the answer if you divide 50 by 20. Do you see how simple math can be if we simplify things?


100-1,000+1,500-x=581. What is the value of x?

It's easy to solve for x - just start with the numbers you have. We know the end point is 581. So start at the beginning. 100 minus 1,000 leaves -900, plus 1,500 gives you 600. X then would be 19, as 600 minus 19 is 581! Simple!


The square root of 9 is what?

To determine the square root, you must find the number that is multiplied by itself to bring you to the final total, 9 in this case. Basic multiplication tables tell us that the number is 3, as 3 multiplied by 3 is 9.


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