Starting from today, every month you save $500 into a bank account with earns interest at an annual rate of 4%. How much money do you have in the account at the end of 4 years?

500. x 12 = 6,000. + 4% (240.)

500. x 24 = 12,000. + 4% (480.)
500. x 36 = 18,000. + 4% (720.)
500. x 48 = 24,000. + 4% (960.)

Yr 1 = 6,000. + 240. = 6,240.00
Yr 2 = 12,000. + 480. = 12,480.00
Yr 3 = 18,000. + 720. = 18,720.00
Yr 4 + 24,000. + 960. = 24,960.00