It occurs when the interest is reinvested rather than paying it out. Interest in the next period is then earned on the principal sum plus previously accumulated interest.
The formula is:
Where:
A = final amount
P = initial principal balance
r = interest rate
n = number of times interest applied per time period
t = number of time periods elapsed
Abdul deposited P=$4000 into an account with r=2.6% = 0.026 compounded quarterly. Since there are 4 quarters in a year, n=4. We are required to calculate the amount in the account after t=10 years.