Calculate Simple Interest, Principal, Rate or Time when 3 Values are Known

By Deb Russell, About.com Guide

When the amount of interest, the principal and the time period are known, you can use the derived formula from the simple interest formula to determine the rate. I=Prt becomes r=I/Pt. Remember to use 14/12 for time and move the 12 to the numerator in the formula above. Get your calculator and check to see if you're right.

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• Calculating Interest: Principal, Rate and Time are Known
• Calculating Interest Earned when Principal, Rate and Time are Known
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