math formula (multi column) / If statement

You always have more flexibility with Column Expressions because you can “write code” if a manner of speaking, but I thought you guys wanted to stay with the Math Formula node

@takbb , regarding the order of the columns, it is actually putting them in the same order it found them, but it is not what you expected to see

To understand this, you have to run the loop 1 iteration at a time - well, at least the first iteration to understand what is going on.

This is from the first iteration:

So, essentially before it starts the loop it has all the columns except for the Quantity columns, and at first iteration, it adds the Quantity April wherever it was found and processes whatever it’s processing within the loop.

In the next iteration, it will be again the same columns but instead of Quantity April, it will do Quantity May. What you have to realize is that it will again have 6 (5 input columns + Result column) columns, which it will try to append after the 6 columns from the first iteration, so now you have 12 columns.

And so on until the loop is done. That is why you end up with 30 columns at the end of the loop (Node 23), in that same order of the 6 columns repeated. And of course, the column filter only filters out the columns that you want to remove, keeping the order as is, and that’s how you end with the 6 columns from the first iteration, and then a pair of Quantity and Result after that.