Question 698786
to solve this type of problem go backwards through the statement and do the opposite of what it says!
So we start with six and instead of dividing by 9 we multiply by 9. This gives
6 X 9 = 54
next we subtract 33 instead of adding 33
54 - 33 = 21
Next we double instead of halving
21 X 2 = 42
Finally we add 12 instead of taking 12
42 + 12 = 54
The number you started with was 54! 
(Just to check, try running through the statement using 54 as the number first thought of and see if you end up with 6.
Here goes...
54 - 12 = 42
{{{42/2}}} = 21
21 + 33 = 54
{{{54/9}}} = 6
yay! the check works so our answer is correct)