Create Function To Change Date into Week Number

Hi All,

Im trying to save myself some time and create loads of new functions in my Perosnal macro workbook.

At the moment i'm trying to create a function that converts a given date into its corresponding week number.

i know the formula to do this is as follows:

=TRUNC(A1-Date(Year(A1),0,0)+6))/7)

Where A1 = the cell reference that contains the date.

Obviously my function would start as follows:

Function WeeknUmber(Date1)
     WeekNumber = ???????

I'm just not sure on how to work the formula into this function?

Please help

thanks for reading my thread everyone