fx-9860GII
Mixed fraction ⇔ improper fraction
On a Casio calculator you can convert an improper fraction into a mixed fraction
H SHIFT F⇔D
Be sure to select RUN-MAT mode with SET UP Input/Output Line.
Example 1
To calculate
H
2 + 1 ab/c 2 EXE SHIFT F⇔D
Be sure to select SET UP Frac Result d/c.
Example 2
To convert the decimal number 2.75 to the mixed fraction 
2 · 7 5 EXE 2.75 SHIFT F⇔D 2.75 2.75
and to the improper fraction
SHIFT F⇔D 2.75