PERIODS()
 Computes the number of payment periods necessary to repay a loan
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 Syntax

     PERIODS(<nCapital>,<nPayment>,<nInterestRate>)
        --> nNumberPayments

 Arguments

     <nCapital>  Designates the loan amount.

     <nPayment>  Designates the amount of the scheduled periodic payment.

     <nInterestRate>  Designates the periodic interest rate.  1
     corresponds to 100%.

 Returns

     PERIODS() returns the number of payments required to repay the
     <nCapital> amount.

 Description

     PERIODS() computes how often you must make a payment <nPayment> to reach
     the <nCapital> amount at the <nInterestRate> interest rate.

 Note

     .  If the installment payment is smaller than the interest
        amount, repayment lasts forever.  In this case, the function returns
        a value
        of -1.

 Example

     How many months do you need to pay back a $4000 loan at an annual
     interest rate of 9.5%, if you want the $200 monthly payments?

     nRate  :=  0.095/12             // Monthly rate
     ? PERIODS(4000, 200, Rate)      // Number of periods