cumulative total
 

I have a client who wants me to include on his monthly invoice, every
consultant who has worked on the contract, the number of hours each
consultant has worked that month and the number of cumulative hours each
consultant has worked. I have tried a simple formula that I found in a help
forum but it seems to update all cumulative cells.

Say for instance I have 3 columns:
consultant # hrs worked in Oct # hrs worked total on contract

I may have 10 consultants on 1 project and I need only his cumulative total
in the 3rd column.

Any help would be appreciated.