Esta resposta no StackOverflow deve resolver sua problema.
Para citar:
For numbers get last value with this formula in Z2
=LOOKUP(9.99E+307,A2:Y2)
or for text...
=LOOKUP("zzz",A2:Y2)
or for either...
=LOOKUP(2,1/(A2:Y2<>""),A2:Y2)
all the formulas work whether you have blanks in the data or not......