If:
- D = outstanding debt of $1 million.
- P = payment owed of $100,000.
- A = actual payment of $110,000.
The process looks like this:
First, subtract the payment owed from the actual payment.
A - P = $110,000 - $100,000 = $10,000
Then divide the result by the outstanding debt to figure out how much of an overage you're dealing with:
(A - P) / D = $10,000 / $1 million = 0.01
Now multiply that by 100 to get a percentage:
0.01 x 100 = 1%
You'll need to do this for several months in a row to see if your single monthly mortality is growing, shrinking, or staying the same.