Skip columns from XIRR function
 

Hi everyone,

I've been trying to calculate the XIRR for a series of periodic cashflows
using the following data:

Oct-06 Nov-06 Dec-06 Dec-06 Jan-07 Feb-07 Mar-07
(10,000) 1,000 1,500 (7,500) 1,500 2,000 2,500

The problem is that the fourth column (Dec-06) is the total of the
preceeding columns and I want to skip it in calculating the XIRR function.

If anyone can help me on this