What is the formula to calculate the present value of an annuity?

What is the formula to calculate the present value of an annuity?

The formula to calculate the present value of an annuity is:

PV = PMT * [(1 - (1 + r)^(-n)) / r]

Where:
PV = Present Value
PMT = Periodic payment or cash flow
r = Interest rate per period
n = Number of periods