Recently I started to read again Brealey & Myers's "Principles of Corporate Finance" (an older edition I hold it since I attended to the university course on Economics and Corporate Finance as a part of the curriculum in Electronics Enginering at the University of Bologna), since I need to evaluate the profitability performance of some projects I am involved with. The two authors use the NPV method which assumes (more or less explicitly) the use of compound interest, perhaps familiar to all of us, and, en passant, mention the existence of the simple interest. Inspired by curiosity, I searched for applications where the interest rate is required to be simple, but I was not able to find anything outside examples in textbooks and lecture notes, so my question is: what are the uses of simple interests in current economy?
Edit on behalf of the comments. I am asking this question because I am curious to see some examples and understand the reason why, in these cases, the simple interest is used. In my understanding, the use of compound interest is extremely natural since it corresponds to the intuitive concept that the invested money (continuously) produces a cash flow that is implicitly reinvested (at least up to the moment when the intial investment + the interest has to be payed back), thus it implicitly generates a (continuous time) conpound interest rate: for the simple interest I am not able to imagine such an intuitive explanation.