I am an undergraduate student, and I just started a course called "Mathematics of Compound Interest." Most of the students in the class are taking actuarial exams (I myself have not decided what I'm doing), so the course is geared toward that kind of study (it's not proof oriented, etc.). The suggested text is Theory of Interest by Kellison, but the professor told me that given my background (Calc I, currently taking Calc II), it's too advanced for me, and we won't be going that deep in class anyway. So does anyone have a suggestion of a text that follows similar material on a simpler level that I would understand? Thanks a lot. I really like having a textbook in addition to lecture notes.