Autofill Forumal Down Column
 

I am currently working on setting up a call cost register for my workplace.

I have set up formulae in columns D, E and I, beginning at row 4 (so, D4, E4
and I4) to calculate various figures; however, I need a macro that will
either:

1. Autofill those formulae down the column regardless of whether the
previous row was fully completed (column I is the final column of the
register and does not always require an entry); or,

2. Allow those 3 formulae to function within every following cell of those
columns (for instance, the formula is D4 will function in ever cell from D4
to D65536)

I have very limited VBA knowledge, so if anyone could help it would be
greatly appreciated.

Autofill Forumal Down Column
 

Just in case it helps, and since I didn't think of it earlier, these are the
formulae I am currently using:

Column D: =INT((C6-B6)*1440)

Column E: =ROUNDUP((D6/6),0)

Column I: =IF(AND(G6="Y", H6="Y"), (E6*11), "")