How can I assign a formula for the whole column?

I am looking for some input regarding this matter in Excel 2003. My spreadsheet has the same formula in all cell of a particular column by the use of row and indirect functions. It is using almost six thousand rows. Presently, I have to copy the formula to each cell. I think this is increasing the calculation processing time of Excel. Will it possible to assign a formula for a given column? By this I can give one formula for whole columns and this can reduce the calculation time. Please help me.
