Again it’s to show your work. Unless you’re your own boss, someone should be reviewing the cash collection and making sure the totals are right. Often cash collections and even AR departments list and sum up the transactions received. You aren’t exporting your calculations from your phone. The next most common replacement is excel and the amount of people who will hard code totals rather than use a sum function will blow your mind. That’s why these are still used. I can see that you actually went through and added the figures up, and you can’t just hardcore a total that you think is correct/matches with these. It’s a check against mistakes.