Actuarial Science

Discount is described as the present value multiplied by the interest rate. This concept has been explained lucidly by Professor J Kulkarni in the chapter given by the link below. The chapter also explains the concept of annuities, premium and payment contained within an annuity. Do take a look.( The first portions of the video appears muted though)
https://www.youtube.com/watch?v=UuvZL21PYkA