I need help in forecasting. so any help will be highly
appreciated.

I have a data as follows:
Jan05 Feb05 Mar05 Apr05 May05 June05...... Dec05 Total
103 107 ... ... ... .... 1700

Based on Jan05 and Feb 05 data I need to fill up Mar 05
to Dec05 data to get a pre determined total of 1700. Is
there any quick way or formula or function to solve this??
Thanks for your help.