Step by step
The question
Question: A loan of $5000 at 12% for 2 years is paid monthly.
Find the monthly payment.
1 Read the numbers
P is the money borrowed: $5000.
r is the yearly rate: 12% is 0.12.
n is how many times a year: 12.
t is the time: 2 years.
2 Per payment
Interest is added each month.
The rate for one month is i: r over n.
0.12 divided by 12 is 0.01.
And N is how many payments: 12 times 2 is 24.
3 Use the formula
The payment each month: PMT = P times i, over 1 minus (1 + i) to the power negative N.
We put the numbers in: 1 plus 0.01 is 1.01.
4 Work it out
The top: 50.
With a calculator, 1.01 to the power negative 24 is about 0.787566.
1 minus that is 0.212434.
Now the top over the bottom.
50 divided by 0.212434 is 235.3674 and a bit.
Lenders round up to the next cent: 235 dollars and 37 cents a month.
Careful!
That pays back only the loan.
The interest must be paid too.
5 Check
Let's check with the first month.
The interest that month is 5000 times 0.01: $50.
The rest of the payment, 185 dollars and 37 cents, pays the loan down.
So the loan gets smaller every month.
It makes sense!
Let's look back.
First: read the numbers.
Then: per payment.
Then: use the formula.
Then: work it out.
Last: check.