On Sat, 6 Jun 2009 11:16:01 -0700, Totonno
wrote:

How do I compute the rate of return on a stream of payments that are not
equal other than by trial and error?

Use the IRR function.

"Returns the internal rate of return for a series of cash flows represented by
the numbers in values. These cash flows do not have to be even, as they would
be for an annuity. However, the cash flows must occur at regular intervals,
such as monthly or annually. The internal rate of return is the interest rate
received for an investment consisting of payments (negative values) and income
(positive values) that occur at regular periods."
--ron