What is the formula to figure out the following finance problem?

I want to pay off my car loan by Feb. 1st 2011. I currently owe $47199.97 on a car loan that has an 8.99% APR. My payment of $226.31 is due on the 11th of every month. I have $2000 to put on the loan on 8/31(in addition to my payment for that month) and also $1000 to put on the loan on Feb first which I would like to be the last $1000 to pay off the loan. So I have 6 more payments to make in the meantime (8/2010,9/2010,10/2010,11/20100,12/2011 and 1/2011). I need to know how much I should pay on those 6 payments so that by the time 2/01/2011 rolls around I will owe exactly $1000 and can just pay it off. The interest is what throws me off, I don't know how to figure this out. please help....thanks!

You need to know if the Interest is calculated as Monthly or Semiannual, In this case i guess its Monthly.

$47,199.97 is what you owe, APR/12= 0.749167%

Effective Annual Rate = (1+0.007492)^12 -1 = 9.3698%

Future Value (Money owed) = 47,199.97 x 0.09.3698= 4,422.55 + 47,199.97 = $51,622.52

Monthly Payment = 226.31 x 6 = $1,357.86

You plan on paying 2,000 on Aug. Total Already planned on paying off = 3,357.86

51,622.52 - 3357.86 = $48,264.66

Exra Equal payments of 5 months = 48,264.66 - 1,000/ 5 = $9,452.93

Leaves you with a last payment of 1,000 = $48,264.66 - (9,452.93 x 5)

No car loan company would leave their clients glueless as to how much money they need to pay each month. You can just call them to ask.

So this is a text book question isn't it?