how to find compound interest when time is in months?
['A = Accrued Amount (principal + interest)', 'P = Principal Amount.', 'I = Interest Amount.', 'R = Annual Nominal Interest Rate in percent.', 'r = Annual Nominal Interest Rate as a decimal.', 'r = R/100.', 't = Time Involved in years, 0.5 years is calculated as 6 months, etc.']