Using a scientific calculator to solve formulas that contain fractions?

I am using a Nexxtech Scientific Calculator (#6518205) and having a lot of trouble calculating fractions! I have had it for a while and no longer have the instructions, and failed to find any online. I am not very strong in math and have no idea what my settings should be like or what a majority of the buttons do so I am pretty lost...

I am working on chemistry, and am trying to calculate formulas for the conversion of Farenheit to Celsius. The formula is C=5/9x(F-32), 5/9 being a fraction. I am using a button on my calc that looks like :Ab/c, where b/c is in superscript and the symbol it imputs looks like the lower right corner of a box. I have tested several different numbers to calculate, where I know the answers, and here is my problem: all of the answers contain sig figs after the decimal point, but my calculator does not display them! Instead, it only shows the whole number (which i correct), the a symbol that looks like a small "u" followed by a calculated fraction! This fraction is of no use to me, but the numbers after the decimal point DEFINITELY are. Am I using the wrong button, or is there some sort of setting I need to change to make it function the way I want? I have tried resetting it and it made no difference.

I will be monitoring this question for the next half hour or so if you think you can help but need more info... THANKS!