Hi Consider please the following table

| Name | E1 | E2 | E3 | E4 | Res | |--------+----+----+----+----+-----| | Entry1 | | | | | NP | | Entry2 | 10 | 20 | 30 | 40 | 10 | #+TBLFM: $6=if("$2" == "nan" , string("NP"),($2+$3+$4+$5)/10);E The last column contains a string NP if the corresponding cell in the second column is empty. However when I consider | Name | E1 | E2 | E3 | E4 | Res | |--------+----+----+----+----+-----| | Entry1 | | | | | NP | | Entry2 | 10 | 20 | 30 | 40 | 10 | | Entry3 | 10 | | 20 | 30 | nan | #+TBLFM: $6=if("$2" == "nan" , string("NP"),($2+$3+$4+$5)/10);E The last row behaves strangely the cell in the second column is *not* empty but the cell in the third one is, nevertheless the cell in the last column contains the string nan, which I don't understand. Any help would be appreciated Thanks Uwe Brauer