[Vince]

per cent is French and literally means: per hundred. If you keep that in mind it isn't all that difficult.

Add percentage:

pawn Код:

newvalue = oldvalue * (1.0 + (15.0 / 100.0));

Subtract percentage:

pawn Код:

newvalue = oldvalue * (1.0 - (15.0 / 100.0));