Using the RATE function with only the required arguments:
Using the RATE function with the optional arguments:
The arguments for the RATE function are:
Argument  Required?  Description 

rate  Required  The interest rate per period. 
nper  Required  The total number of payment periods in an annuity. 
pv  Required  The present value â€” the total amount that a series of future payments is worth now. 
fv  Optional  The future value, or a cash balance you want to attain after the last payment is made. If fv is omitted, it is assumed to be 0 (zero), that is, the future value of a loan is 0. 
type  Optional  The number 0 or 1 and indicates when payments are due. If type is omitted, it is assumed to be 0:

guess  Optional  Your guess for what the rate will be.: 