How do federal reserve banks as well as the federal government typically calculate simple interest?

Federal Reserve Banks and the federal government typically calculate simple interest using the formula: ( I = P \times r \times t ), where ( I ) is the interest earned, ( P ) is the principal amount (initial investment), ( r ) is the annual interest rate (expressed as a decimal), and ( t ) is the time period in years. This calculation assumes that interest is not compounded, meaning it is only earned on the original principal throughout the specified time frame. Interest rates and terms are often determined by prevailing economic conditions and monetary policy goals.