Yohn, are you looking for a standard calculation of percentage you typically find on a calculator? If so, you could try something similar to this:
/* Want 33% of entered value */
DEFINE VARIABLE vPercent AS DEC.
DEFINE VARIABLE vValue AS DEC.
vValue = 112.
vPercent = 33.
DISPLAY vValue * (vPercent / 100).
Hipe this helps.
