automation of YTD calculation

[MPP]

How can I automate a YTD calculation ?I have my data from january to
september and my YTD column. When I insert a column for october I have to
update the formula to calculate the YTD.

 

[John C]

How is your data set up? column references, row references, where new data
would be entered, and what is your current YTD formula?

 

[MPP]

jan to oct are set from D to M, YTD is set at right of oct. When I will
insert column for nov (N) how can I automate YTD calculation so I don't have
to change formula each time (YTD will then be in O and must be sum of jan to
nov)