## About This Quiz

Doing mental arithmetic may have been a bore back in school, but it was a bore that you actually should have thanked your teacher for pushing on you. The ability to flip figures around in your mind, or at least with a pencil and paper, is actually really important to a functioning brain. Arithmetic is like reading, a basic function of literacy. Subtraction is an exercise for your mind, much like doing your stretches helps your body to function at its most effective level. If you can't do it, it doesn't mean you're stupid, it just means you're less effective than you might be; and if you can do it but you choose not to, then that's like sitting on your mental butt all day when you're capable of playing all kinds of fun sports!

Taking your brain out for a quick series of calculations is like taking it to the gym. It might ache a little or get a little tiresome after a while, but once you're done, you'll feel virtuous. If you keep it up, you'll realize your mind has gotten leaner and better, and the workouts get easier. Think of this quiz as testing out your current mental fitness. Are you an arithmetic couch potato, are you ready for SEAL training, or are you somewhere in between? Let's find out!

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This one's not too hard. We're really just warming you up here. The right answer is 105!

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An even number minus a smaller odd number? That means the answer must be positive and odd.

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This one, you just have to do in your head. You know from the 7 and the 2 at the ends that it ends in a 5, so your focus is on the middle number.

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It's just 2! Sometimes in this quiz, we'll include questions that might look hard but are actually really easy. We don't want you to overwork here!

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An even number minus a smaller even number? That means you are looking for an even answer that's still a positive integer.

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An odd number minus a smaller odd number? That means the answer must be positive and even.

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It's 277! It's not a hard one, but you might have worked too hard and thus landed on the wrong answer. The key is not to think too hard when you don't have to!

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Even number minus smaller even number equals positive even number. Hence, 514.

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It's a nice easy one you really can do at a glance. It's 100!

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Big number minus bigger number? The result? Negative number!

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A smaller number minus a huge number is a big negative number. Hence, -621.

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Not a trick question, this one. It's just a nice clean zero!

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We're getting some negative answers here - and they're going to get more common as we go, so look out! It's -757.

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If you think of this as 822.0 minus 10.4, you instantly know you're looking for a .6. So the answer is the only one with that.

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It's 10! We put the .0 to mess with you. We bet you didn't fall for it, though.

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A round number minus an odd number is an odd number! So if you forget the decimal points for a moment, you can just see the answer at a glance.

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It has to end in .7! So it's 57.7, even if you don't do the rest of the sum. Mental arithmetic is often about leaping to the conclusion via the shortcut (but, you know, do then check that it was the right instinct).

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It has to end with a .28! And it has to be less than 1 total!

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It has to be smaller and it has to end with .01. Hence, 8.01!

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It's an integer minus something with a .01, so you know it'll end in a .99. Hence, 101.99!

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It has to have a .1 and it has to be smaller than the original! Hence, 366.1!

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It's a deduction. Just treat the decimals like you would any three-digit number to get 1.18.

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This one's simple! It's 1.5.

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Anything ending .0 that deducts something ending 0.01 has to end in .99. There's just one option!

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It has to be 0.1 someplace because of the .9. Given the multiple choice, really you don't need to do more math than that!

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Yep, it's just 111. Couldn't be simpler!

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It's a tiny number minus a slightly greater number. Hence, a negative result.

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A negative number minus a positive number is an even more negative number. Hence -199.

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It's a negative, then minus another negative. The latter two minus signs cancel out, so you add the 494.

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-1450 is the right answer, as this is a negative number minus a positive number. So you get a negative result!

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A negative minus a positive is two negatives. So the right answer is -199.9.

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Two negatives here - one negative, then a positive that is deducted. So you get -111.

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It's zero! You have a negative, and then a double negative. So the negative and positive cancel out for a zero.

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The first is negative, and the second is positive but you're deducting it. Hence, you end up with both being totally negative, for -340.

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