# Cumulative rental payments over a period of time

What's the formula to figure out how much money you make on total rental payments over a period.

Say each month I rent out 2 cars, and get $50 for each. The length of the rental period is indefinite. • Jan, 2 cars =$100, $100 total • Feb, 2 cars =$100 + $100 for Jan's two cars,$200 total

• Mar, 2 cars = $100 +$100 for jans + $100 for Febs,$300 total

How do I do this in a formula if I wanted to calculate, say 4 a month, at $50 payments, over the next 23 months. How much would I make? I'm stuck • If you don´t know the rental period of each car then you cannot calculate it. – callculus Mar 15 '17 at 20:56 • I want to be able to calculate "for XX months, assuming I rent YY cars each month (the same), at ZZ rate, I'll have$\$" – gelat Mar 15 '17 at 22:17