GMAT Prep DS Question

[khwaja.shoaib]

What is the remainder when the positive integer n is divided by the positive integer k, where k > 1


(1) n = (k+1)^3
(2) k = 5


OA = A

Can someone please explain this?

[amitganguly2k12]

Substitute k = 2,3,10.

Each time you will get 1 as remainder.So the OA.

thanks

[pritesh.suvarna]

(1) n = (k+1)^3 / k

Since the numerator is k+1 and denominator = k, the remainder will always be 1

A - Suff

(2) k = 5

n not defined.

Ans = A

Thanks
Pritesh

[gayatri.ganpaa]

Another way of solving this --
a) If you expand (k+1)^3 --> k^3+3k^2+3k+1 When you divide n/k- all the terms are divisible by k, except for 1. Therefore, remainder is 1.

b) does not give you any information about n

[Ben Ku]

Another way of solving this --
a) If you expand (k+1)^3 --> k^3+3k^2+3k+1 When you divide n/k- all the terms are divisible by k, except for 1. Therefore, remainder is 1.

This is a good algebraic proof for statement 1.

The plugging in numbers approach works; however, you cannot plug in and evaluate all values. I would suggest to look for the algebraic approach first.