@ denis and DrPhil (not the TV guy)
I was originally confused as well about the numbers shown in this thread even though I already knew that numbers are traditionally shown differently in South Asia. I think that we are dealing with a cultural difference. I get mixed up about lahks and crores when I am doing research and have to look them up every time.
http://en.wikipedia.org/wiki/Indian_Numbering_System
Even then, however, the problem is not stated clearly. An interest rate of 12% per annum does not generate the monthly payment indicated. The total amount paid does not equal the product of the monthly payment.
Here is what I THINK is happening. Because the total interest paid is just about 12,000 for a loan of 100,000 with a term of one year, our poster is wondering whether or assuming that he is paying 12% interest. That is wrong of course.
If our poster wants to use a spreadsheet, put balance due in column A, start with 100,000 in the first row and in the following rows compute new A = prior D. In column B, compute interest due as 0.179 * amount in column A. In column C, show 9334 as monthly payment. Compute D, remaining balance due at end of month as A + B - C. Because 1.79 is not exact, column D will not show zero in column 12, but it will be close enough to show that the effective interest rate is about 1.79% a month or (as denis said way back when) about 21.47% a year.
