How to figure compound interest

Compound interest formula (annual)

A = P (1 + i) ^n

where A = total/final amount

P = principal/initial/beginning amount

i = interest rate

n = number of years

OR if interest was calculated in different time periods such as monthly, semiannually, fortnightly, weekly, daily etc

A = P (1 + i/k) ^n

where k = number of periods in that year

n = kt = number of periods * number of years

e. g. if interest was calculated monthly for 2 years

k would be 12 & n would be 12*2 = 24