What is the formula for calculating simple interest?

The formula for calculating simple interest is expressed as I = PRT, where I represents the interest earned, P is the principal amount (the initial sum of money), R is the rate of interest (expressed as a decimal), and T is the time the money is invested or borrowed, typically in years.

This formula effectively captures the essence of simple interest, which is calculated on the original principal alone, without compounding. Thus, the interest grows linearly over time, directly proportional to both the principal amount and the time period of the investment or loan at the given interest rate.

The other options provided do not align with the correct principles of simple interest calculation. The inclusion of terms like T^2 or the operations in other options do not reflect the correct relationship that simple interest depends on only the principal, the interest rate, and time.