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Simple Interest

Simple interest is computed on the amount of the principal of a loan. That principal is multiplied by the rate of interest; the resulting figure is then multiplied by the time over which the loan will be repaid.

Simple Interest on a $100 Loan
Annual Rate
 Time 5% 6% 7% 8% 9% 10% 15% 20%
1 month .4167 .5000 .5833 .6667 .7500 .8333 1.2500 1.6667
6 months 2.5000 3.0000 3.5000 4.0000 4.5000 5.0000 7.5000 10.0000
12 months 5.0000 6.0000 7.0000 8.0000 9.0000 10.0000 15.0000 20.0000
24 months 10.0000 12.0000 14.0000 16.0000 18.0000 20.0000 30.0000 40.0000
36 months 15.0000 18.0000 21.0000 24.0000 27.0000 30.0000 45.0000 60.0000

 

Compound Interest

Compound interest is computed by multiplying the sum of the principal and the accrued interest by the rate of interest. This calculation must be refigured each time the principal is compounded. To determine the approximate number of years it will take for the principal to double, divide the interest rate percent into 72.

Compound Interest on $100 Principal, Compounded Annually
Annual Rate
 Time 5% 6% 7% 8% 9% 10%
6 months 2.50 3.00 3.50 4.00 4.50 5.00
1 year 5.00 6.00 7.00 8.00 9.00 10.00
2 years 10.25 12.36 14.49 16.64 18.81 21.00
3 years 15.76 19.10 22.50 25.97 29.50 33.10
4 years 21.55 26.25 31.08 36.05 41.16 46.41
5 years 27.63 33.82 40.26 46.93 53.86 61.05