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