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.
Aparna said:
1 decade ago
How could 30k has come in this answer please anyone explain me.
Narendra said:
1 decade ago
As take remainder that is 3 square it 9 divide it by 5 answer will be 4.
Jeevitha said:
1 decade ago
Let the number be x.
x = 5k+3.
Let us take k = 1.
Then x = 5(1)+3.
x = 8.
So, square of 8 = 64.
When 64 is divided by 5.
Remainder is 4.
Therefore, answer is 4.
x = 5k+3.
Let us take k = 1.
Then x = 5(1)+3.
x = 8.
So, square of 8 = 64.
When 64 is divided by 5.
Remainder is 4.
Therefore, answer is 4.
Purushothaman said:
1 decade ago
Exclusive me, I have little doubt how could come to 30 k please explain me.
Ankita said:
1 decade ago
If we subtract the remainder by number i.e. x - 3 and divide it by 5 we will get zero.
Therefore (x - 3)/5 = 0.
x = 3.
Now 3^2 = 9.
& 9/5 the remainder will be 4.
Therefore (x - 3)/5 = 0.
x = 3.
Now 3^2 = 9.
& 9/5 the remainder will be 4.
Bharathi said:
1 decade ago
For example x = 13.
We will divide 13/5 we get reminder as =3.
The square of the 13 has 169.
169 is divided by 5 we get reminder as 4.
So answer = 4.
We will divide 13/5 we get reminder as =3.
The square of the 13 has 169.
169 is divided by 5 we get reminder as 4.
So answer = 4.
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.
Balaji Shinde said:
1 decade ago
5+3 = 8.
So square of 8 is 64.
If 64/5 remainder will be 4.
So square of 8 is 64.
If 64/5 remainder will be 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?
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.
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