mattapraveen wrote:

If [(243)^x]X[(463)^y] = n, where x and y are positive integers, what is the units digit of n?

(1) x + y = 7

(2) x = 4

The above question is from MGMAT. The answer given is A.

But i believe, even (X=4) will also give the solution.

As X=4, the power of 3 in the expression [(243)^x]X[(463)^y] would always be 3^4n and the units digit will always be 1.

Can some one comment on this. Bunuel your help would be very much appreciated.

Let me try ... i am not even 1% what bunuel is ..

The reason why x=4 is insufficient because we dont know anything about Y, so if x=4 and y is 1, the unit digit will be 3, if y=2 then, unit digit will be 9 and so on.

So, i think it is necessary to have exact value of both the variants before reaching to the unit digit.

Had it been 5 as base , then it would not have made any difference because the unit digit is anyhow gonna be 5 only.

am open to comments .. correct me if i am wrong anywhere

HTH

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