Question: how to calculate compound interest rate per annum?
Answer: Calculate Accrued Amount (Principal + Interest) A = P(1 + r/n)nt
Calculate Principal Amount, solve for P. P = A / (1 + r/n)nt
Calculate rate of interest in decimal, solve for r. r = n[(A/P)1/nt - 1]
Calculate rate of interest in percent. R = r * 100.
Calculate time, solve for t.