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Fast Math - Square Roots

In this quiz the answers change every time you play! Solve these randomised square root problems as fast as you can!
Answer must correspond to highlighted box!
All answers are integers
Too easy? Try the harder version: Up to 200 squared
Quiz by
Stewart
Featured Quiz
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Last updated: November 3, 2019
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More quiz info >>
First submittedNovember 3, 2019
Times taken57,220
Average score70.0%
Rating4.54
Quiz and answer stats >>
Friends stats >>
2:30
Enter solution here
0
 / 20 guessed
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Keep scrolling down for answers and more stats ...
Problem
Solution
√169
13
√144
12
√64
8
√529
23
√49
7
Problem
Solution
√3136
56
√3249
57
√1521
39
√3025
55
√1600
40
Problem
Solution
√121
11
√289
17
√36
6
√1296
36
√900
30
Problem
Solution
√9
3
√196
14
√1
1
√4
2
√1089
33
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42 Comments
Nathaniel
+14
Level 77
Nov 10, 2019
I made a Fast Math - Roots Quiz in August, not that anyone cares.
Stewart
+27
Level 68
Nov 10, 2019
But yours wasn't randomised, and is cube roots too. This is just square roots.
JSSTyger
+3
Level 53
Nov 13, 2019
I am the damn champion. 100% first time with 8 seconds left.
rphxx
+5
Level 72
Dec 28, 2019
1:24 left
81928128
+22
Level 63
Jan 6, 2020
did it in 43s on my first try. simple trick: estimate the first digit by ignoring the last two digits and taking the square root, then guess the last digit by looking at the last digit.
Malbaby
+3
Level 70
Apr 7, 2020
Can I call you '819' for short?....... anyway you are correct with your tip, I got 19/20 having a go your way........ i don't know why it works ...... but it does!
AntiMatter8192
+1
Level 77
Apr 24, 2020
I had a similar trick, just guessed numbers using the first 3 digits and using the last digit to see if the root was odd.
chickenthewing3
+1
Level 47
May 13, 2025
I have an even easier method. Just use a calculator.
Scythebrine
+1
Level 55
May 16, 2025
Then what's the point?
benf415
+23
Level 70
Jun 23, 2020
No estimation required:

>100 means it's 10+

>400 means it's 20+

>900 means it's 30+

>1600 means it's 40+ and

>2500 means it's 50+

And the last digit:

1 means either 1 or 9

4 means 2 or 8

5 means 5

6 means 4 or 6 and

9 means 3 or 7

EcceHomo
+2
Level 85
Jul 8, 2020
ben415 nice tip, got them all using this method.
sergeantmalice
+1
Level 56
Jun 9, 2022
@benf415 you're a genius, helped me pass this
chickenthewing3
+1
Level 47
Sep 19, 2025
1:37 left
joeythelemur
+3
Level 81
Apr 10, 2020
Easy, Tyger
souhhcong
+1
Level 48
Aug 23, 2021
who

who asked

zonocci
+1
Level 57
Dec 27, 2024
only used 50 seconds
Pufferfish952
+1
Level 43
Dec 22, 2019
100% first try with 19 seconds left i could have done it faster but for somereason i got stuck on one
mf3
+23
Level 90
Apr 7, 2020
Now you'll remember that the square root of one is one.
Henceforth516
+4
Level 88
Apr 6, 2020
There's a lot of time on the clock - got 100% with a minute left and a lot of guessing. It's easy to just go in order of lower to higher and guess very quickly.
Stewart
+1
Level 68
Apr 7, 2020
The time is the same as other "fast math" quizzes. 2:30 with 20 questions! Remember if this is too easy you can always try the harder version in the description!
dianalove
+1
Level 70
Apr 6, 2020
Funny!
Abknerd7
+1
Level 50
Apr 16, 2020
1st try ma bois
Yoshimano
+1
Level 66
May 18, 2020
0:33 .. phew
MrKenny
+1
Level 68
Jun 23, 2020
1:27 remaining héhé
ftozom
+1
Level 62
Jun 30, 2020
1:54 remaining on first try
maxism
+1
Level 70
Jun 23, 2020
Wasn't expecting to be able to do this one, but did it with a lot of guesswork lol. Out of interest, anyone got any good techniques?
Dimby
+2
Level 83
Jun 23, 2020
I feel like my technique is what I remember from school. The final digit of your answer determines the final digit in the squared number. 1 -> 1, 2 -> 4, 3 -> 9, 4 -> 6, 5 -> 5, et cetera. Once you know any square ending in a 4 must have come from a 2 or a 4, you're down to only several guesses that make sense. Then you can just keep in mind that if it's under 100, the answer must be under 10. If it's under 400, under 20. Under 900, under 30. Under 1600, under 40. Under 2500, under 50. I used this method and solved it with a couple minutes remaining on my first try.
ander217
+2
Level 74
Jun 23, 2020
I'm terrible at math, but I lucked out in getting clues for answers that ranged mostly from 37 through 51, so after I worked one out it was easy to look at the last digit of the remaining clues and fill in the others based on the first answer. Then I had four really easy ones, which left me plenty of time for the few I actually strugged with. Phew!
AmyD85
+3
Level 75
Jun 23, 2020
Maybe this is why I majored in English ...
sacheth9
+1
Level 65
Jun 27, 2020
Great quiz! Thanks for including the top bar, looks amazing this way!
kapib811
+1
Level 27
Dec 11, 2020
pajace
1ProximaCentauri
+1
Level 53
Mar 21, 2021
got them all in 42 secs
stylus
+1
Level 79
Oct 10, 2021
there could be a harder version of this quiz where the answers you've already got don't stay shown, so you can't use them to help estimate the remaining ones. would be challenging but sounds like some people in these comments would like the challenge (and before anyone suggests it, i don't have the quizmaking skills to do this myself).
BuaDencosMen
+1
Level 21
Oct 3, 2022
I did all of them in just 45sec I DID NOT CHEAT!
etfdyhw
+1
Level 27
Dec 13, 2022
done with 1:56 left. nice quiz
SorenReview
+1
Level 52
Jan 23, 2023
26 Seconds Left
potatoooooooooes
+2
Level 61
Dec 5, 2023
19
Phobophobia
+1
Level 41
Feb 17, 2025
Can you give me the link to your quizzes I want to subscribe to you
Stewart
+1
Level 68
Feb 17, 2025
They do not have any quizzes
MrFatFat
+1
Level 45
Apr 22, 2024
Not horribly difficult. I took 2:20.
mrzli86
+1
Level 99
Dec 17, 2024
I did't
rhager842
+2
Level 29
Feb 28, 2025
I got 2025 as a question and learned that this is the first perfect square year since 1936. The next one will be almost 100 years from now
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