The Math Behind Excel’s CUMIPMT() & CUMPRINC() Functions

I published the math behind the CUMIPMT() & CUMPRINC() functions at the bottom of my spreadsheet for the post Annuity – Excel Functions and Math. I think it got lost in all the annuity math. When I Google the math for these two functions, my blog doesn’t show up until the 6th or 7th page, depending on the wording of the search. I see the question asked without a real answer, so I am posting the formulas again by themselves. I am also doing it because it is my blog and I can.

Download “CUM

 

cum1

Also the math for a single row of a simple amortization schedule:

cum2Download “CUM

Don Pistulka
Don Pistulka

Retired Credit Union CFO - Finance
Background: over 40 years in investments, asset/Liability management, banking, securities trader.
Worked for: California Credit Union, WesCorp, CalFed S&L, Crocker Bank, Carroll McEntee, Federal Home Loan Bank Board (D.C.), Western Asset Management, Security Pacific National Bank.

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