Using last column in Numbers I would like to subtract the last column of a specific row. Since the number of columns is always changing, I need to get it dynamically. I figured there is a function that gives you the number of columns of a row. But I am not able to tell Numbers to use it (because I don't know the syntax).
I'm not 100% clear what you're asking to do since you haven't posted any of the contents of the sheet, but you can use the INDEX, ROWS and COLUMNS formulas to get what you want. INDEX() will return the contents of a cell within a certain range of cells, and you can use rows() to count the number of rows and columns() to count the number of columns, depending on exactly what you need. Without knowing how ranges are defined and things are labelled it's hard to be more specific, but I think that will get you started in the right direction.

If that doesn't help, maybe you could post what you've tried and give us some example data &amp; formulas.