Aptitude - Square Root and Cube Root - Discussion

Discussion :: Square Root and Cube Root - General Questions (Q.No.14)

14. 

How many two-digit numbers satisfy this property.: The last digit (unit's digit) of the square of the two-digit number is 8 ?

[A]. 1
[B]. 2
[C]. 3
[D]. None of these

Answer: Option D

Explanation:

A number ending in 8 can never be a perfect square.

Pawan Goyal said: (Oct 26, 2010)  
hw this could be possible that a number ending with is not a perfect square

Kala said: (Aug 13, 2011)  
Please explain.

M.V.Krishna/Palvancha said: (Sep 11, 2011)  
Hello pawan and kala.

The two digit numbers are from 10 to 99.

The numbers with 8 in units place are.

18, 28, 38, 48, 58, 68, 78, 88, 98.

These numbers do not have a perfect square (s*s).

So answer is none of these.

Hope you understand.

Veena said: (Nov 9, 2012)  
Number ending with 0, 1, 4, 5, 6, 9 are the perfect squares rather than these are not perfect squares.

Aarti said: (Feb 5, 2015)  
Number ending with 8 is not a perfect square.

Balu said: (Jul 5, 2015)  
I can't understand so please explain again.

Abi said: (Feb 10, 2016)  
2 = 4.
3 = 9.
4 = 16.
5 = 25.
7 = 49.
9 = 81.
10 = 100.

As you can see all squares have 0, 1, 4, 5, 6, 9 in units place.

So if we have 2, 3, 7, 8 in units place it square root is not perfect.

Jayram said: (Jul 19, 2016)  
If the units place is 1, 2, 3, 4, 5, 6, 7, 8, 9.
Square of all number = 1, 4, 9, 16, 25, 36, 49, 64, 81.
Then, take unit value for all squares =1, 4, 9, 6, 5, 6, 9, 4, 1.

And approx is 2, 3, 7, 8.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.