How do you change 0.58333333333 into a fraction?

If the number in question is 0.58333333333 exactly, than the only fraction you can convert it to is 58,333,333,333/100,000,000,000.

However if you mean for the 3's to repeat infinitely, than the result is much cleaner. If you multiply 0.58333333333 by 12 then you get 6.9999999996. If the 9's repeat infinitely this is 7, so your fraction is 7/12.