ANSWER:

You must estimate an approximate amount and add a little more to be on the safe side and give it to poor and needy Muslims.

QUESTION: Previously,I didn’t knew that we cannot pay bank charges like maintenance fees using the interest money. Now I don’t remember how much of the interest money I used to pay charges or did I even actually use them to pay charges or not as the bank usually cuts off the charges automatically. I only remember that I gave the interest money in charity. What to do now?