How can a cell value be rounded down to the nearest even number
If the cell value is always positive, try the following
=FLOOR(A1,2)
If the cell value is always negative, try the following
=-CEILING(-A1,2)
If the cell value can positive or negative, try the following
=CHOOSE(SIGN(A1)+2,-CEILING(-A1,2),0,FLOOR(A1,2))
Hope this helps / Lars-Åke