Hi eamon at hom
Doing fraction on the Sharp El 531W really isn't that bad. I had to use pictures
because, the symbols will not transfer over to your posting for me to show you. When you select the [ON/C] this clears the calculator of previous calculations and, data so that they won't interfere with your new calculations.
Let take the first example where a mix number is being added to a improper fraction. Because I used the [a^b/c] key this makes the calculator display the answer in a mixed fraction format or, a proper fraction format. If I press the [a^b/c] key again after the answer the format will change to a decimal format. The fractional formats are displayed in a mixed number, improper or, proper fraction formats. A improper fraction is really a proper fraction number with the top number (numerator) is greater than or equal to the bottom number (denominator).
[ON/C]  [a^b/c]  [ [a^b/c]  [+]  [a^b/c]  [=] mixed number results. Now let's do the same calculation as a improper or, proper fraction format.
[ON/C]  [a^b/c]  [+]  [a^b/c]  [=] still a mixed number result. Even though I enter the fractions in a improper and, proper fraction formats the calculator will still display in a mixed number format. This is because the calculator first displays as a mixed number if it can. If it can't then it will display the value as a proper fraction and, never as a improper fraction. To convert from a mixed number to a improper fraction format if the calculator did not convert it to a proper fraction, I have to use [2ndF] [d/c] keys on the command line.
This show a little more complex raised power use of the [a^b/c] key.
This shows the [2ndf] [x^-1] keys being used to calculate fractions.
When I first saw this question being asked it, was answered with just use the / command. Which that isn't really a good answer because, in math we like to use elimination. If you use the / command eventually
the numbers are going to be rounded off and, your not going to be able to eliminate anything. If you have any further question on how to preform fractions with this calculator be sure to post your comment and, I'll be glad to help.