# Thread: Consumer Math, fixed rate mortage

1. ## Consumer Math, fixed rate mortage

I just can't seem to calculate this on my calculator:
find the monthly payment necessary to amortize a $75,000 mortage at 9.5% annual interest for 15 years. This is how I calculated it: 75,000(.095/12)(1+.095/12)^(180) divided by (1+.095/12)^(180)-1 I am not getting the right answer which I know is 783.17 Could it be my calculator? 2. Originally Posted by Suwanee I just can't seem to calculate this on my calculator: find the monthly payment necessary to amortize a$75,000 mortage at 9.5% annual interest for 15 years. This is how I calculated it:
75,000(.095/12)(1+.095/12)^(180) divided by (1+.095/12)^(180)-1

I am not getting the right answer which I know is 783.17

Could it be my calculator?
I can't verify the procedure, but I get 783.169.

Half steps:
$\displaystyle 75,000 \left ( \frac{.095}{12} \right ) \left ( 1+\frac{.095}{12} \right ) ^{180} = 2454.9147747917$
and
$\displaystyle \left ( 1 + \frac{.095}{12} \right ) ^{180}-1 = 3.1345933049123$

-Dan

3. Originally Posted by Suwanee
I just can't seem to calculate this on my calculator:
find the monthly payment necessary to amortize a \$75,000 mortage at 9.5% annual interest for 15 years. This is how I calculated it:
75,000(.095/12)(1+.095/12)^(180) divided by (1+.095/12)^(180)-1

I am not getting the right answer which I know is 783.17

Could it be my calculator?

(75 000 * (.095 / 12) * ((1 + (.095 / 12))^180)) / (((1 + (.095 / 12))^180) - 1) = 783.168512.