On Thu, 11 Dec 2008 12:37:44 +0100, "Niek Otten" wrote:

I get #NUM too.
Your numbers are quite big. If I divide all numbers by 100, I get 26.43%.


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Kind regards,

Niek Otten
Microsoft MVP - Excel

Niek,

Why do you think these "large" numbers result in the #NUM error (which I get
also in Excel 2007).

I thought Excel uses an iterative technique to solve for IRR, finding the
interest rate for which the NPV is zero.

It must have something to do with the way Excel calculates IRR internally, but
....

I set up to solve the IRR iteratively.

I used the OP's original data in B2:B11

E3 will be my "guess" for the IRR.

I then set up these formulas:

E3: 10%
G2: =B2
G3: =B3*(1/(1+$E$3)^ROWS($1:1))

Fill down to G11

G13: =SUM(G2:G11)

I then used Goal Seek to set G13 to 0 by varying E3. And that comes up with
the proper answer. The answer is the same as the IRR answer to 15 decimals.

In other words, implementing what I thought was the IRR technique in a
different way did not result in any error, and returned the correct answer.
--ron