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 ?
0
1
2
4
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.

Shriram deshmukh said:   9 years ago
Dividing number by 5 its means multi of 5.

(5 * 1 + 3) = 8--> 64/5=> rem 4.
(5 * 2 + 3) = 13--> 169/5=>rem 4.
(5 * 3 + 3) = 18--> 324/5=>rem 4.

And so on.

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.

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.

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.

Pavishka said:   4 years ago
We assume the nearest value + reminder.

i.e 5 + 3 = 8
8/5 = 1 (reminder=3)
And square of 8 is 64
64/5 = 12
The reminder is 4 so,
ans = 4.
(6)

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.

Raja virat said:   9 years ago
Let the number be 23.
When 23 is divided by 5 we get remainder as 3,
Then, square of the number = 23 * 23 = 529.
So, 529/5 = 4.

Timothy Mayanja said:   2 years ago
I don't understand the following step,
(25k^2 + 30k + 9).

Please explain to me in detail.
(2)

Bhuiyanislam said:   8 years ago
Difference - remainder = question - 1.
5 - 3 = x - 1.
x = 2 + 1 = 3.
3^2 = 9.
9/5 = 4.

Reshma said:   1 decade ago
Difference - remainder = question - 1.

5-3 = x-1.

x = 2+1 = 3.

3^2 = 9.

9/5 =4.


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