The interest you earn each year is added to your principal, so that the balance doesn't merely grow, it grows at an increasing rate.
The amount which you have invested.
An interest rate is the cost of borrowing money, or conversely, the income earned from lending money. Interest rates are expressed as percentage of the principal per period.
calculate principal plus interest or principal or rate or time.
The number of compounding periods in one year.
Here is the formula for finding the compound interest