WARNING: in order to find n, you must multiply the number of years by the number of payments/year

Use the Present Value formulas when you know (or want) the value at the beginning. Use the Future Value formula for when you want to know the value at the end of the deposits.

When looking for the Present Value, and payments are given (Example: You want to receive $1000 each year, how much do you need to set aside?)

When looking for the Payments, and present value is given (example: a loan for $5000, what is the payment?)

When investing a fixed amount each period, and looking for the value after n periods