3 Method Of Single Interest Calculation

a. Fixed Dividing Method

The fixed dividing method is used if the single interest rate is a divisor of 360, 1 year is considered 360 days, the interest rate i% /year and the period of liver flattening.

a.1 Formulas of the Fixed Dividing Method

B = interest rate/fixed divider
Amount of interest = Amount of interest rate/fixed divider

a.2 Sample Question of Fixed Dividing Method

Determine the total interest earned by the cooperative from the table of savings and loan cooperative customers "X" with a single interest rate i = 9% / year and 1 year is considered 360 days!

Resolution:
Fixed divider = 360/i = 360/9 = 40

To determine the number of interest rates, consider the table below:

The sum of interest rates is $17,325,000

B = $17,325,000/40
B = $433,125

So the interest amount is $433,125

b. Comparable Percent Method

This method is used if a single interest rate is not a divisor of 360, 1 year is considered 360 days, interest rate i% / year and payback time t days.

b.1 Formulas of Comparable Percent Method

B = interest rate/fixed divider
amount of interest = amount of interest rates/fixed divider

b.2 Examples Problems of Comparable Percent Methods

Please determine the total interest earned by the cooperative from the table of savings and loan cooperative customers "Z" with a single interest rate i = 11%/year and 1 year is considered 360 days!

Resolution:
The interest rate i = 11% is outlined to = 10% + 1%
Then i = 10%

Fixed divider = 360 / i
Fixed divider = 360/10
Fixed divider = 36
Amount of interest rate = $ 15,850

Amount of interest = Total interest rate / fixed divider
Amount of interest = $ 15,850,000 / 36
Amount of interest = $ 440,277.78

Interest is proportional to 1% = (1% / 10%) x $ 440,277.78
Interest is proportional to 1% = $ 44,027.78

So the total interest of the 11% interest rate is = $ 440,277.78 + $ 44,027.78 = 484,305.78.

c. Same Size Percent Method

This method is used if 1 year is considered 365 days, so there are not many tribes that give the result to round 365, then usually the interest rate is 5% so the divisor remains = 365/5 = 73

c.1 Formula of The Same Size Percent Method

B = interest rate/73
amount of interest = amount of interest rates/73

c.2 Example of Same Size Percent Method

Please determine the total interest earned by the cooperative from the savings and loan cooperative saving table "T" with the interest rate i = 6.5%/year and 1 year is considered 365 days!

Resolution:
The interest rate i = 6.5% is outlined to be = 5% + 1.5%
First determined the amount of interest rate for i = 5%

Fixed divider = 365/i
Fixed divider = 365/5
Fixed divider = 73

Interest amount = total interest rate/73
Interest amount = $15,200,000/73
Interest amount = $208,219.18

Interest comparable to 1.5% = (1.5% / 5%) x $208,219.18
Interest comparable to 1.5% = (3/10) x $208,219.18
Interest comparable to 1.5% = $62,465.75

So, the total interest rate of 11% = $208,219.18 + $62,465.75
So, the total interest of the interest rate is 11% = $270,684.93

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Reference :

The To'Ali book of sales and accounting mathematics books

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