# HELP with a math project - amoritization?

I need help with math how do I raise to the -360 it is an amoritization project I am using an online calculator http://www.math.com/students/calculators/source/sc... I need to raise 1.00583 to neg 360 then I need to look

_____898.333_____________

1- (1.00583) -360

My end result should be a mortgage paymetn of 1024.00

for a 154K house at 7% interest and 30 years but I am getting a payment of 897.07 per month which is wrong - because i compared the caculations with online mortgage calculators- this being a math class i have to show my work.... HYElp !

### 4 Answers

- MerlynLv 71 decade agoFavorite Answer
better idea, don't use that calculator

get the power toy calculator for windows http://www.microsoft.com/windowsxp/downloads/power...

the expression you need is 898.333 / (1 - (1.00583) ^ ( -360))

another idea is to get a TI emulator. http://mathematics.mc.maricopa.edu/seims/TI-Emulat...

- Wile E.Lv 71 decade ago
It's easier if you use the PMT function in Microsoft Excel. When I crunched the numbers, I got a monthly payment of $1,020.43.

Here's what I did:

In Excel, click on ƒx on the standard toolbar.

Click on Financial in the left window and PMT in the right window.

Click OK.

Now, just fill-in the blanks:

Rate = 0.0058 (7%, or 0.07, divided by 12 months)

Nper = 360 (30 yrs. x 12 mo./yr.)

Pv = 154000

Fv = 0

Type = 0

Click OK

The answer will be negative (I don't know why), but for all intents and purposes, your monthly payment is shown to be $1,020.43.

- gugliamo00Lv 71 decade ago
I believe your formula for computing the payment is incorrect.

http://www.math.com/tables/general/interest.htm

Scroll down to "Loan Balance"

It should be

B = A (1 + r/n)ʷ - P [(1 + r/n)ʷ - 1] / [(1 + r/n) - 1] where w=nt=12x30=360

0 = (154000) (1 + .07/12)³⁶⁰ - P [(1 + .07/12)³⁶⁰ - 1] / [(1 + .07/12) – 1]

Solve for P

I worked it out and get payments of 1024.57

- 1 decade ago
Can you not use Windows calculator? Click view/scientific. It has "x^y" which works faster than this online one. You'd press 1.00583 [x^y] 360 [+/-] [=]

same is true for your online calculator. it's printed [y^x] tho.