autofilling formulae across columns

[JZB]

hi guys

can you confirm the quickest way i can autofill a formula across columns.

I know how to autofill down to the lastrow

Range("AI2:AI" & Cells(Rows.Count, "A").End(xlUp).Row).Formula =

but how do get this to run across the s/sheet

Thanks

Jon

[mdmackillop]

Range(cells(1,1),cells(1,columns.Count).end(xltoleft)).Formula =