Introduction to interest:

http://www.mathsisfun.com/money/interest.html

SIMPLE INTEREST

 I = Prt  

• I = interest  [$]
• P = amount borrowed (called “Principal”)  [$]
• r = interest rate   [%]
• t = time    [years]

COMPOUND INTEREST

 A = P(1+r)^t  

• A = actual amount owed (total debt)   [$]
• P = amount borrowed (called “Principal”)    [$]
• r = interest rate     [%]
• t = time    [years]

Information on compound interest:

http://www.mathsisfun.com/definitions/compound-interest.html

SIMPLE INTEREST PRACTICE PROBLEMS:

http://www.mathopolis.com/questions/q.php?id=1702&site=1&ref=/money/interest.html&qs=1702_1703_1704_1705_3749_3750_3751_1706_1707_1708

COMPOUND INTEREST PRACTICE PROBLEMS:

http://www.mathopolis.com/questions/q.php?id=2294&site=1&ref=/money/compound-interest.html&qs=2294_2295_2296_2297_2298_2299_2300_2301_2302_2303