Biff wrote...
this is still a bug. COMBIN should *only*
return integers or error values.

I agree and had always assumed as much. This little exercise proves
otherwise.

=MOD((COMBIN(9,3)-84),1)

Returns 1.
....

Actually, it returns 0.999999999999986. And don't get me started on
MOD.

With all boils in need of lancing in Excel, what does Microsoft do?
Give it a nose job.