Division creating many columns

I am trying to calculate the % decrease of air pollution in two seperate scenarios and put the answer in a new column variable

However, when I do this it creates the same number of columns as in my table already, all populated with 0, and 1 column the correct answer.

When i split up this code and do it seperately it occurs during the division step

I am using the following code:

Table.PnC_Removal = (((Table.Concentration_S1 - Table.Concentration_S2)/ Table.Concentration_S1)* 100)

Answer 1

[Steven Lord]

Use element-wise division not matrix division.

Table.PnC_Removal = (((Table.Concentration_S1 - Table.Concentration_S2)./ Table.Concentration_S1)* 100)

Note the extra period that's part of the division sign.