Can you help me with a little algebra?

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I know you can use a calculator but I want to be able to calculate a mortgage without.
The correct answer is $ 1,199.10
30 year mortgage at a 6% interest rate with a $ 200,000 loan.

Here is a link to the formula
http://steadfastfinances.com/blog/wp-content/uploads/2010/02/Amortization-Equation-example.jpg

Here is what I bashed into my calculator

200 000 * 0.0005 = 100

0.06 / 12 + 1 = 1.005
1 – 1.005 = -0.005
-0.005 – 12 * 30 = -360.15

100 / -360.15 = -260.15

What did I do wrong?
I already have the algebra I just don’t know how to interpret it.

3 Comments
  1. Reply
    ayush
    April 29, 2011 at 10:47 pm

    200 000 * 0.0005 = 100

    this is wrong. it should have been

    200 000* 0.005 not .0005…

    try that. 🙂

  2. Reply
    mathmom28
    April 29, 2011 at 11:03 pm

    Well, you made three mistakes.

    First, 0.06/12 = 0.005 and not 0.0005
    200,000 * 0.06/12 = 200,000 * 0.005 = 1000

    Second -12*30 is an exponent. You’re not supposed to multiply it with the rest of denominator
    Third exponent -12*30 applies ONLY to (1+0.06/12) and not to all of 1 – (1+0.06/12)

    1 – (1+0.06/12)^(-12*30) = 1 – (1.005)^-360 = 1 – 0.1660419 = 0.8339581

    1000 / 0.8339581 = 1199.10

  3. Reply
    Taurean
    April 29, 2011 at 11:09 pm

    First of all 200 000 * 0.005 = 1000 (006/12 = 0.005 and not 0.0005)

    Secondly in the expression (1+ 0.06/12) -12*30 is the power and not simply subtraction and multiplication

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