What is Compound interest?
Money is said to be lent at compound interest (C.I).if the interest is not paid as soon as falls due,but is added to the Principle after a fixed period,so that the amount at the end of period becomes the principal for the next period.If a is the amount,C.I(compound interest) is the compound interest,p is the principle ,R is the Rate,and t is the time,then
Note:
If interest is paid half yearly;time is doubled,and the rate is halved.
Compound interest(C.I) for one year  is equal to the simple interest for one year.