Can You Pass This Basic 3 Digit Number Subtraction Test Without Using a Calculator?

EDUCATION

Zoe Samuel

5 Min Quiz

Image: Shutterstock

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!

What is 727 - 115?

Odd minus odd is always even!

Advertisement

What is 227 - 122?

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

Advertisement

What is 892 - 133?

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

Advertisement

What is 477 - 392?

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.

Advertisement

What is 401 - 399?

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!

Advertisement

What is 982 - 124?

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

Advertisement

What is 825 - 523?

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

Advertisement

What is 377 - 100?

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!

Advertisement

What is 856 - 342?

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

Advertisement

What is 633 - 533?

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

Advertisement

What is 823 - 901?

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

Advertisement

What is 101 - 722?

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

Advertisement

What is 737 - 737?

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

Advertisement

What is 232 - 989?

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

Advertisement

What is 822 - 10.4?

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.

Advertisement

What is 27.7 - 17.7?

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

Advertisement

What is 103 - 27.1?

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.

Advertisement

What is 82.3 - 24.6?

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).

Advertisement

What is 6.26 - 5.98?

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

Advertisement

What is 9.01 - 1.00?

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

Advertisement

What is 102 - 0.01?

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

Advertisement

What is 388 - 21.9?

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

Advertisement

What is 11.1 - 9.92?

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

Advertisement

What is 28.8 - 27.3?

This one's simple! It's 1.5.

Advertisement

What is 30.0 - 2.01?

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

Advertisement

What is 327 - 90.9?

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!

Advertisement

What is 888 - 777?

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

Advertisement

What is 0.01 - 0.08?

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

Advertisement

What is -100 - 99?

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

Advertisement

What is -322 - -494?

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

Advertisement

What is -983 - 467?

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

Advertisement

What is -99.9 - 100?

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

Advertisement

What is -22.2 - 88.8?

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

Advertisement

What is -828 - -828?

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

Advertisement

What is -170 - 170?

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.

Advertisement

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!

Explore More Quizzes