Originally posted on 07/28/2014:
Well, you are forgetting the first week's interest is my point.
After a 1000 payment on 1530 in the second week and 2% (lol) interest on the outstanding is 10.6pts for a total owed of 540.6, not 510.
If your math was correct, the lender would only get 10pts of interest on a 1500 loan for 2 weeks.