Are You a Master of Mental Math?

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

Take 4x2 and you have 8? It's just 100 times that as it is 40x20. So the answer is 800.

Simple subtraction. 17-16 is 13. Keep better care of your apples, please!

Easy, it's 24. Why? Because 24 can be divided by both 3 and 4 and it falls into the range of 20 to 30 as requested in the question.

It's 9 tablets. Let's break it down. You would take at 11 a.m., 11:15 a.m., 11:30 a.m., 11:45 a.m., 12 p.m., 12:15p.m., 12:30 p.m., 12:45 p.m. and 1 p.m.

Well 18 and 18 is 36, so half of 36 is 18. That simply enough. 17 and 17 is 34, so therefore half of 35 must bet 17.5. Hmm, that's a roundabout way to get there but it makes sense, doesn't it?

Anything times zero is zero! The answer is 0. This is a very basic rule of math taught to students at an early age. I hope you remembered it.

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

The first thing to take note is if there are any zeros after the decimal, if there are then these numbers are the smallest. Then it is just a case of treating them like normal numbers. For instance, 0.91, we can see as 91 which is bigger than 89 (or 0.89) and 90 (0.9). The other numbers we dealt with.

If you multiply the 6's you get the gist of the answer. 6 x 6 would be 36, so 0.6 x 6 must be 3.6. Or add them. 0.6 plus 0.6 is 1.2, plus 0.6 is 1.8 and so on.

The answer is 3 hours, 00:00. It travels at 30 miles per hour so it will cover 90 miles in three hours, which would also make the time 00:00.

Well, breaking it down sees 200 times 10 equalling 2000. That's simple enough. Do that twice and add and you get 4000.

The 200 immediately stands out of all the answers. 200 times 5 is 1000. So 1000 divided by 5 is 200. It works the same either way.

An isosceles triangle will have one angle of 90 degrees. All the sides of the triangle are equal in length. This means that the other two angles must both be 45. The total amount of a degrees in this triangle would be 180.

A little bit of a tough one here. But we know that 20 times 20 is 400. So 20 times 22 must be 440. And therefore 440 divided by 22 must be 20.

The easiest way to find the value of x is to subtract 19 from 39. And the answer is 20. Quite simple, really, but yes, that wasn't a very difficult 'solve for x' question was it?

Add 733 and 200, rounding up the 191. That will give you 933, then you must minus 9 for the rounding up and that leaves 924. How did you work it out? Did you use the same method?

So we have to ask ourselves, to solve this, we need a number multiplied by itself that is 81. And if you know your 9 times table, it's staring you in the face. 9 times 9 is 81. So the square root of 81 is simply 9.

Let's start with the big numbers. We see 900 next to -899 so that leaves us with 1. 1 plus 99 plus 47 - 10 is 137. And finally, add 137 to 79. So that is 130 plus 70 and 7 plus 8, which is 215.

Bob has $30 more than Fred. Why? Well, Bob only has one $100 bill. Fred has 5x$10 ($50) and a $20. Add them together and you have $70 in total for Fred. So now it is easy to see that Bob has $30 more than Fred.

OK, add it this way. 6 and 4 is 1 plus the 1 left over from the 0.4 and in total it is 2.0. Makes sense, doesn't it?

35 plus 44 is easy added. 3 plus 4 is 7 and 5 plus 4 is 9, so it's 79. Now subtract that from 98 and you get 19. And that is your answer!

You still have 32 lemons. READ the question carefully! Sometimes math is not just about the numbers, it's about understanding what is expected of you. Now that will keep you on your toes!

The easiest way to get to the answer is to take 0.7 add another 0.7, which is 1.4 and a further 0.7 which is then 2.1. Can you see the correlation where 7 times 3 is 21?

The answer is 341. How? Well a 1000 minus 829 leaves you with 171. Then add 150 which is 321. If you take 80 from 100 you have 20, so add that to the 321 and it becomes 341! Yay!

12 x 6 + 6 will give you your answer and it is 78. Why plus 6. Well, that is the half a foot the question asked to add.

Very easy, with straightforward numbers like 200, it's just simple math. 900 minus 700 leaves 200, but don't forget about the 28 which you must add back to get the full answer.

The red tin is $16, the blue tin is $9. Why? Well, 16 and 9 make up $25 which is what Bob paid. And 16 - 9 equals 7, which the problem tells us is the difference between the two paint prices.

This one we will do a little differently. -899 plus 99 leaves -800. 1000 minus 800 leaves 200 and add 13 and you have 213, the answer we wanted.

0.1 +0.85 comes to 0.95. All that is needed to make up 1 is another 0.05. That is the answer.

Fairly simple if you break it down. 13 times 10 is 130, then add another 13 as the question asks. Do you agree that that gives you 143?

Well if he can run 15 miles in an hour, 30 minutes is half of an hour, so to get the answer, take half of how far he runs in an hour. That leaves you with 7.5 miles. Well done, Bill. That is impressive.

22 times 10 equals 220, that's simple enough. Therefore, 220 divided by 12 must equal 10. Do you agree?

We learned earlier that the square root is a number multiplied by itself to give us an answer. So what number, multiplied by itself, gives us 25. That's 5 and that's your answer!

The answer is 10. How? Well take 220 minus 30, that equals 190. But the overall answer is 200. That makes x equal to 10!.