Here is an actual sequence of key presses to do a calculation with fractions:
                
                To use fractions, enter the inches and press "inch". Then enter the numerator (the number on top 
                of the fraction) then press one of the denominator keys. (Those are the ones at the top which go
                from 1/2 to 1/64.) For example, to enter 5 7/16, you'd press:
                
                Press:
                
                5
                "Inch" button
                7
                "1/16" button
                
                You'd then see 5 7/16 in the box just above the keyboard. To add 2 1/4 to this, press the "+" button then:
                
                2
                "Inch" button
                1
                "1/4" button
                
                Then press equal.
                
                If you're working with a length less than an inch, don't use the Inch button. For example, to enter 3/4,
                press:
                
                3
                "1/4" button
                
                The thing that makes this different from other types of fraction calculators is that is specific for 
                measurements, e.g., 1/2, 1/4, etc. You can't enter 4 2/3 for example because that isn't a
                measurement. The reduced functionality actually makes it much easier to enter fractions.