Determine the principal amount
Identify the interest rate
Identify the time period
Use the simple interest formula: Interest = Principal × Rate × Time
Convert the rate to a decimal
Convert the time to the same unit as the rate
Multiply principal by rate and time
For compound interest, use: Amount = Principal × (1 + Rate/n)^(n×Time)
Subtract the principal from the final amount to get interest
Check units and calculations carefully