6^2/3 is the same as saying 6^2 and then cube rooting the answer. (this can also be done the other way around by cube rooting first and then squaring, both ways are acceptable but for larger numbers rooting first and then squaring is easier and likewise for smaller numbers squaring then rooting can be easier.
In this case 6^2 = 36
and so 36 cube rooted= 3.3 (3 significant figures)
If your still having trouble just reply and ill get back to you.