Hi @aliaga
i dont know which activity activity you are using , but you can try this linq query in the assign activity . It will handle the null values too using If
sum = dt1.AsEnumerable().Sum(Function(row) If(row(“Oct_2020”).ToString.Equals(“”),0,CDbl(row(“Oct_2020”)))
here sum variable in final will give you the sum of values of column Oct_2020