My best guess is n^3:n^3-n, making the answer 60, but I have no idea what the real answer is.

27 is 3 * 3 * 3 and 24 is (3 - 1) * 3 * (3 + 1)

64 is 4 * 4 * 4 and _60_ is (4 - 1) * 4 * (4 + 1)

Thanks. I would've failed this question :)

56.8…

Given that they've defined "::" differently to the usual "as" the answer could be anything. More specifically, the answer is f(64), where f(x) is wharever was in the head of the guy who made the question.

The same goes for the "what is the next number in this sequence" questions: unknowable given the information provided.

The answer is "x, such that x is an element of the set containing Everything."

But personally, if asked this question suddenly, I would've gone for the simplest: 61, because 27 - 24 = 64 - 61.

just find an f(x) where f(x) is in [a,b,c,d] and f(x) isn't so arcane that its unrealistic that the examiner would've had it in mind.

63, because it's always a pair of an even and odd number.