Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 31)
31.
On dividing a number by 5, we get 3 as remainder. What will the remainder when the square of the this number is divided by 5 ?
Answer: Option
Explanation:
Let the number be x and on dividing x by 5, we get k as quotient and 3 as remainder.
x = 5k + 3
x2 = (5k + 3)2
= (25k2 + 30k + 9)
= 5(5k2 + 6k + 1) + 4
On dividing x2 by 5, we get 4 as remainder.
Discussion:
37 comments Page 3 of 4.
Narendra said:
1 decade ago
Thanks for the shortcut.
Lopa said:
1 decade ago
Thanks rajesh for this method.
Kiran said:
1 decade ago
Let the num is 3. Then square of 3 is 9 so 9/5 remainder is 4.
Neha nagar said:
1 decade ago
For this kind of question consider any no. Suppose 13/5 gives remainder 2 then the square of 13 means 169 when divided by 169 gives remainder 4.
Sanju said:
1 decade ago
Thanks Neha for easy shortcut.
Amit said:
1 decade ago
x/5 = 3.
Square of (x/5)/5 = 9/5 = 4.
Square of (x/5)/5 = 9/5 = 4.
Naina Sanghvi said:
1 decade ago
Number is 5k+3.
This number when divided by 5 will give the remainder as:
5k/5 = 0+3/5 = 3 i.e; 0+3 = 3.
Now (3)^2 = 9.
Remainder when 9/5 = 4.
This number when divided by 5 will give the remainder as:
5k/5 = 0+3/5 = 3 i.e; 0+3 = 3.
Now (3)^2 = 9.
Remainder when 9/5 = 4.
Nil.dhongde said:
1 decade ago
@Rajesh rao method is very wrong. It doesn't follow the rules everywhere. This method is like hit and try. The original universal method is given itself in problem.
Wanna check it out if Mr Rajesh rao's method is right or wrong. Try this.
So here is similar problem for those, who used to use other shortcuts method.
if certain number is divided by 7 gives 6 as remainder. What will be the remainder if square of the same number is divided by 7?
Wanna check it out if Mr Rajesh rao's method is right or wrong. Try this.
So here is similar problem for those, who used to use other shortcuts method.
if certain number is divided by 7 gives 6 as remainder. What will be the remainder if square of the same number is divided by 7?
Sayali said:
10 years ago
Easiest way.
We have ask square of the no:
So 3 square is 9.
9/5 remainder is 4.
4 is the answer.
Apply this method to sum no 41.
We have ask square of the no:
So 3 square is 9.
9/5 remainder is 4.
4 is the answer.
Apply this method to sum no 41.
Udaya santhi said:
1 decade ago
The number taken as n.
n = 5*q+3.
The square of the number is n*n=(5q+3)^2.
That number is divisible by 5.
Therefore, [(5q+3)^2]/5={[(5q)^2/5]+[2(5q)(3)/5]}+[9/5].
The flower bracket whole number is divisible by 5. But 9/5 = remainder is 4.
n = 5*q+3.
The square of the number is n*n=(5q+3)^2.
That number is divisible by 5.
Therefore, [(5q+3)^2]/5={[(5q)^2/5]+[2(5q)(3)/5]}+[9/5].
The flower bracket whole number is divisible by 5. But 9/5 = remainder is 4.
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