# Can you help me with a little algebra?

Deal Score0

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

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. 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

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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