In worksheet 'X' I have in column A annual periods (Jan '12 to Dec '12) and column B (Jan '13 to Dec '13) and so forth for a period of 25 years with associated costs in each of the columns.

In another worksheet 'Y', I have in column A semi-annual period (Jan '12 to June '12 and column B (July '12 to Dec '12) and so fother as above.

I simply need to develop a formula that takes the annual costs in worksheet 'X' and drops it into the semi-annual cells in worksheet 'Y' - so in effect dividing the annual cost by 2 each time and then copying this along all colums (over 25 year periods).

Any help would be appreciated.

Regards

Ben