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

By: Zoe Samuel

Can You Pass This Basic 3-Digit Number Addition Test Without Using a Calculator?
Image: Shutterstock

About This Quiz

Remember how we all used to say, "But Miss Mathteacher, we can just use a calculator?" and she would put us in our places by saying, "You won't always have one with you when you're out and about, will you?" Then along came the smartphone, with its dozens of apps, the least of which can calculate far more with a few taps than even Stephen Hawking could do in his head. Oh, how we laughed at Miss Mathteacher! What a fool she was, to be overtaken by technology - and so quickly!

The truth, though, is that she's still right. Being able to crunch numbers in your head is still important. It's partly that you should be able to detect when numbers just feel off; for example, when a bill seems too high or when the expenses on your spreadsheet are adding up funny. It helps you to spot anomalies like an extra item where it doesn't belong or a misplaced bracket or equals sign that's causing the whole spreadsheet to go kerblooey. It's also just plain handy for when you genuinely don't have a calculator; after all, sometimes your phone dies. More importantly, being able to run figures in your head is a baseline life skill, like being able to cook. So many other skills rest on it that letting it atrophy is actually dangerous for your ability to think clearly, and not just about math; it's also about your ability to deduce a conclusion rationally from a premise. It makes you harder to trick, and just plain smarter.

That's why, doubtless, you've kept that part of your brain spick and span ... and now's your chance to prove it!

What is 666 + 583?
1240
1249
The right answer is 1249!
1230
1250

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What is 2.02 + 2.12?
2.22
4.14
That's right, if you have a 2 and another 2, the answer has to be over 4. You don't even need to look after the decimals.
2.00
2.21

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What is 243 + 838?
900
1099
999
1081
The right answer is 1081.

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What is 644 + 644?
1200
1150
1080
1288
The right answer is 1288!

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What is 19.3 + 833?
852.3
Oh, those cheeky decimals! Here they are working together with an integer to mess with your head.
834
845
852

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What is 334 + 924?
777
737
1258
The right answer is 1258!
1499

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What is 833 + 226?
942
958
1059
The right answer is 1059!
998

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What is 728 + 147?
122
797
875
An odd and an even? That's an odd.
804

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What is 737 + 222?
959
The right answer is 959!
550
990
840

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What is 333 + 232?
799
565
The right answer is 565!
787
698

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What is 727 + 737?
1460
1400
1500
1464
The right answer is 1464!

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What is 484 + 0.01?
494
484.01
We're down into the hundredths. Technically, this is still a triple-digit number, it's just much smaller than some.
474
484

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What is 833 + 484?
1316
1318
1320
1317
An odd and an even number always make an odd number.

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What is 501 + 499?
900
1000
The right answer is 1000 flat.
600
1100

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What is 273 + 964?
1022
1237
The right answer is 1237!
988
1050

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What is 2.33 + 10.1?
11.43
12.43
One of these is to one decimal place, the other to two. That's confusing unless you are on the ball.
15.43
20.43

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What is 172 + 182?
273
354
The right answer is 354.
220
351

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What is 100 + 1.00?
200
101
We fooled you with the decimal ... or did we? That's right, we're getting into decimals now.
500
1000

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What is 10.4 + 3.22?
130.2
132.6
13.62
Don't miss those decimals. They'll get the best of you!
132.6

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What is 353 + 111?
464
The right answer is 464.
564
664
764

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What is -284 + 101?
-183
Even though some progress was made back towards 0, it's still negative!
283
-384
-484

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What is 836 + 183?
1019
The right answer is 1019!
1001
999
1011

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What is 9.24 + 82.3?
101.1
82.34
91.54
This looks like it should end in an odd number but actually it doesn't have to. That's because .3 is really .30.
76.01

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What is 743 + 199?
200
942
The right answer is 942.
1042
943

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What is 5.43 + 300?
503.40
305.43
It's an integer plus a decimal, so of course it can't be a round number. You just have to think of the integer as having .00 after it.
350.40
403.55

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What is 721 + 279?
1200
1150
1000
It's 1000 again.
950

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What is 3.12 + 1.09?
40.2
42.1
4.21
They're little numbers so the answer is little!
40.1

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What is 4.53 + 9.99?
14.52
More tricky decimals! But here it's still a fairly simple business to add them up.
1.52
99.43
103.4

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What is 294 + 6.00?
310
299.5
300
300 is a round number and anything ending .00 is a round number.
301.05

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What is 373 + 211?
584
The right answer is 584!
699
564
400

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What is 991+101?
1092
The right answer is 1092.
1022
1011
1024

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What is -100 + -101?
-201
Did you notice the negative signs? If you did, you'll have gotten the right answer.
200
201
2001

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What is -712 + -274?
548
-986
Two negatives, so you just go all the way negative!
-548
-106

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What is -342 + 733?
1075
733
391
There's one positive and one negative number here, so you just deduct the negative from the positive.
-391

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What is -377 + -223?
1000
600
-154
-600
It's two negative numbers here. So you just add them together and put a minus sign in front of it!

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You Got:
/35
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