Calculate Weeknumbers

[gsrai31]

In excel we could use function "=weeknum(cell Ref)" to workout week number based on a particular date, what do I need to do be able to have this function in expression builder in access 2000? or is there another way to do this?
GS

 

[ColinEssex]

Format([DateField],"ww")

Col

 

[gsrai31]

Thanks Colin