Empirical and molecular formula I was doing a homework assignment and I got the question wrong because I was supposed to multiply the empirical formula of $\ce{C6H10S2O}$ by 3 to get the molecular formula.  

I put $\ce{(C6H10S2O3)3}$ and the teacher said it should be $\ce{C18H30S6O3}$.  

My question is: isn't what I put the same thing?
$\ce{(C6H10S2O3)3}$ implies that there are $3 ~ \ce{C6H10S2O3}$ molecules bonded together instead of $1~ \ce{C18H30S6O3}$ molecule. Although they are the same thing, the correct notation is your teachers way because it shows the isometric formula for the molecule. Also if you were using that notation you should have put $\ce{(C6H10S2O)3}$ because $\ce{(C6H10S2O3)3}$ has 6 too many oxygens.