I'm trying to work out interest on short term loans - these are loans that extend to months not years, and are typically repaid in monthly chunks, but I also know that some are repayable in weekly instalments. A 'month' can also have slightly different meanings - a calendar month (28,30 or 31 days), or it could be 1/12th of a year.
I'm looking to create a formula that will allow me to calculate interest (and total repayment) based on these variables - a typical example can be found at the link below. Assuming a £100 loan over 3 months @ 29% per calendar month.
I found this question on the site which seems to be very similar to what i'm asking - monthly compounded interest on a variable interest period (28-31 days). However, I'm no maths expert and the formula in its given state is baffling.
I'd appreciate it if anyone could show working out alongside the formula to help me understand it better.
Thanks in advance.