Is there a excel function that I could use to calculate the numbers of months I have left on a loan given the balance and %rate along with what I want to pay each month?

What I want to do is enter my balance in 1 cell, my desired numbers of months to repay in another cell, and my % rate in the 3rd. And the 4th cell would calculate my amount that I would need to pay monthly.

And...
The same as above, but my monthly payment being entered so I can see how long it would take to pay off the loan......

I looked in the help files but couldnt see what I could use for this....

Thanks

=(a1+((a1*c1/12)*b1))/b1

Check out the PMT and NPER functions in excel help.