pardeepattri wrote:

marcusaurelius wrote:

If x is a positive integer, what is the units digit of x^2?

(1) The units digit of x^4 is 1.

(2) The units digit of x is 3.

oa is B

OA is B

As from the statement 1

You won't be able to find single answer for unit digit. If we'll calculate x^2 it will come as +1 or -1.

From Statement 2

It's given that x = 3 and whenever we will square this we will always get 9 as a unit digit. Try this for 13^2 = 169 or 33^2 = 1089

I think I haven't made any mistake

OA is b but your reasoning is not correct,

First the question clearly says that x is positive and hence there is no question for x being -ve or + ve

Secondly the reason St 1 is no sufficient is that St says the unti digit of\(x^4\) is 1, now if number x has 3 its unit digit then \(x^4\) will have unit digit as \(1 ( 3^4 =81)\) and also when x has unit digit has 7 then also the \(x^4\) will have unit digit as 1

at least two options hence not sufficient