The formula to calculate simple interest is:

\[ I = P \cdot i \cdot N \]

\[ F = P + I \]

Where:

• \(I\) is the total interest earned.
• \(P\) is the principal amount.
• \(i\) is the interest rate.
• \(N\) is the number of periods.
• \(F\) is the future value.