# Simple Interest Calculate Question

by Robert Fong
(Rancho Palos Verdes,CA., USA)

Please give me the equation for the simple interest calculator.

Thank you

### Comments for Simple Interest Calculate Question

 Jan 22, 2010 Simple Interest Formulas by: Dee Reavis The simple interest calculator has 2 equations. The first simple interest formula used is for calculating payments. It is: A = payment amountP = principle or amount of loani = interest raten = number of time periodsThe second simple interest formula is for finding the compounded value of your savings after a given amount of time. It is: There is only one new variable that is not defined above:F = future value of moneyKnowing the formulas helps you to understand how the values are calculated. However, you will want to use either business calculators or spreadsheets to do the actual calculations.

## Interest Paid

by Anonymos

If you've got a loan for 100K at 4.8% annual interest (simple interest), shouldnt that mean you pay \$4800 of interest a year, which would mean in 10 years you pay \$48K of interest? if so, then why do all the loan repayment calculators keep telling me over 10 years the monthly payment would be \$1050--this would only end up being \$26K of interest paid.

Thank you!

The reason that the interest paid is lower is because you are only paying interest on the amount owed in any given month and the amount owed is declining.

An approximation that will get you very close to the right answer is to calculate the interest on the average amount owed. If the beginning loan balance is 100k and the final balance at the end of 10 years is 0k then the average is 50k. 50k x 4.8% x 10 years = 24k. This is very close to the 26k that you calculated. For a more in depth understanding consider this loan amortization schedule.

## COMPOUND INTEREST

by OLUFEMI
(lAGOS, NIGERIA)

What is today's value of a debt of 7,761,010 @ 15% p.a. owed from 11th July,2001?

Assuming that interest is compounded once per year and no payments have been made, the loan would have a payoff of 42,019,574. According to the rule of 72, the 15% interest rate will approximately double the principle every 5 years.

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