Three consecutive natural numbers have a sum of 36. what is the greatest number?

It's 12 because if you divide 36 by 3 (consecutive) it equals 12

If you have three of them, they go in order: 2, 3, 4 and so on.

If the lowest is X then the next two are x + 1  and x + 2. 

Though the question asks you to look for the highest, so I'll call that x, so the other two become "x - 1" and x - 2

So if we add them up to get 36, we get: 

x + (x - 1) + (x - 2) = 36 

Solving for x: 

3x - 3 = 36 
3x = 39 
x = 13