Divisible Factorisations

If a number is even then it can be written in the form $2k$, where $k$ is an integer.  Similarly, if a number if odd then it can be written in the form $2k+1$.  If a number is a multiple of three, in what form can it be written?

Some other things that might be worth considering:

• Can you write $24$ as a product of prime factors?
• Consider pairs of consecutive integers - for example $(3,4)$; $(10, 11)$; $(123, 124)$.  What can you say about the numbers in these pairs?
• Consider sets of three consecutive integers.  What can you say about these numbers in each case?