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What are the current AFRs?
You can find the latest AFRs (or Applicable Federal Rates) on the IRS website at http://www.irs.gov/app/picklist/list/federalRates.html.  The AFR is the interest rate set by the IRS for determining imputed interest, or the minimum interest rate that should be charged on loans and other purposes under the Internal Revenue Code.

Where do I find financial calculators?
http://www.financialcalculators.com/
http://www.bankrate.com/calculators.aspx
http://finance.yahoo.com/calculator/index