Thanks Shyams,

I will give a real example from one of the statements I have.

previous balance=799.20
payments=0
Late Payment Fee=150
Over Due Fee=50

I would like to know what formula the bank used to charge me debit interest of QR 17.92 based on the above figures. The closing balance on that statement for that month was: 799.20+150+50+17.92= 1,017.12