How to report a bug in Excel when Contact Support in Help does not work

John_Oakey 

Please show us your formula.  Copy-and-paste from the Formula Bar.  The following works fine for me:

=NPER(10%/12, 100, -1000)

It returns 10.4848107531311 .

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Aha!  I suspect that you have a typo:  an extra comma; to wit:

=NPER(10%/12, 100,, -1000)

returns 9.64509091983739 (although that rounds to 9.65, not 9.64).

That form incorrectly specifies a "pv" of zero and "fv" of 1000 (signed properly), instead of a "pv" of 1000 and "fv" of zero.

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PS.... Or did you mean that your use of NPER returns negative 9.64 (sic)?

In that case, your mistake might be failing to properly sign cash flows, to wit:

=NPER(10%/12, 100, 1000)    (wrong!)

That does return -9.64509091983739.  But a negative number of periods makes little sense (*).

In Excel, cash flows must be properly signed; that is, opposite signs for inflows and outflows.

In your previous response, you did not identify amounts as inflows and outflows.

If "pv" (1000) is an initial balance (inflow), "pmt" (100) is additional payments (inflows), and "fv" (0) is a final balance (outflow), we cannot have a final balance of zero if the interest rate is positive (10%/12).

So, I interpereted your description to mean, for example:  a loan of 1000 (inflow) and repayments of 100 (outflow), with a final balance of zero.  The choice of signs (and cash flow "directions") is arbitrary, as long as they are opposites.  I chose -1000 and +100.  If the final balance were non-zero (balloon payment), it would have the same sign as other payments (positive).

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(*) Re: ``a negative number of periods makes little sense``

Aarrgghh!  The NPER help page has an example that does return a negative number.  In fact, it is similar to John's example, to wit:  NPER(12%/12, -100, -1000).

That does not make it "right".

Unfortunately, Excel help pages have become increasingly unreliable and less helpful as they have been rewritten over the years.