stef,

There is no default paste formula button.

You need to add a custom button to an existing commandbar - right click a CB, choose Customize, then
under the Categories choose Macros, then drag the smiley face from the commands section to where you
want your button. Right click the smiley face, and assing the macro below to it (First store the
macro in your Personal.xls so that it will be available whenever you have Excel open).  You can edit
the smiley face to some other more appropriate icon....

HTH,
Bernie
MS Excel MVP

Sub PasteFormula()
Selection.PasteSpecial Paste:=xlFormulas
End Sub