P is the principal (the initial amount you borrow or deposit)

r is the annual rate of interest (percentage)

n is the number of years the amount is deposited or borrowed for.

A is the amount of money accumulated after n years, including interest.

When the interest is compounded once a year:

A = P(1 + r)n

( n represents raised to the power of n )

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Monthly = P (1 + r/12)12 = (monthly compounding - raised to the 12th power)