is there a formula for this? so..
year 1 = 3000*1.09 - 1185.16 = 2084.84, principal = 3000, interest = 270
year 2 = 2084.84*1.09 - 1185.16 = 1087.32, principal = 2084.84, interest = 187.64
year 3 = 1087.32*1.09 - 1185.16 = 0, principal = 1087.32, interest = 97.86
is this correct?