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 2 of 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.
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.
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.
Purushothaman said:
1 decade ago
Exclusive me, I have little doubt how could come to 30 k please explain me.
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.
Narendra said:
1 decade ago
As take remainder that is 3 square it 9 divide it by 5 answer will be 4.
Aparna said:
1 decade ago
How could 30k has come in this answer please anyone explain me.
Reshma said:
1 decade ago
Difference - remainder = question - 1.
5-3 = x-1.
x = 2+1 = 3.
3^2 = 9.
9/5 =4.
5-3 = x-1.
x = 2+1 = 3.
3^2 = 9.
9/5 =4.
Sukesh said:
10 years ago
Consider the two reminders first we got 3 before squaring the number.
After squaring and dividing we got 5 as reminder.
So square the 1st reminder 3^2=9. Then, 9/5=4 is the reminder.
After squaring and dividing we got 5 as reminder.
So square the 1st reminder 3^2=9. Then, 9/5=4 is the reminder.
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.
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