Nest CHOOSECOLS inside UNIQUE to extract non-adjacent columns, and use INDIRECT for interactive header dropdowns.

Sometimes hiding certain columns in an Excel spreadsheet can be helpful: Doing so can make spreadsheets easier to read or you may have other reasons to hide them. In any case, hiding columns in ...

Reference: The cell or range of cells or range of cells for which you want to return the column number. It is optional. You will notice that the cell will return the cell number of the cell that ...