proof

[naive raptor]

Prove that all cube numbers are either a multiple of nine or one more or one less than a multiple of nine.

What general approach do I have to these questions?

[fading shale]

so for these kinda questions theres usually a couple approaches but

for this one i want you to consider splitting all integers into 3 groups

multiples of 3, 1 more than a multiple of 3 and 2 more than a multiple of 3