I am having issues with the IRR formula in Excel.  For example:
Year 0: $-60
Year 1: $11

If I calcuate the IRR on excel I get a #NUM error.  However, if I
caculate it by hand using the IRR formula, I get -82%, which makes
sense.

Why is Excel giving me an error?  

Thank you.

IRR in excel is not a very robust function. In the second argument you
need to provide an initial guess, and it will iteratively home in on
the true answer. If you're initial guess is not close enough to the
real answer, it won't converge and give you the #NUM error.

If you supply a number between -.65 and -.99 as the second argument it
will find your -.82 solution, other wise it wont converge.