Is it possible to have a formula in a custom column that performs an arithmetic operation on the values of two other columns? For example, I have a custom column (#words) that contains the number of words in each book, and another custom column (#pages) that contains the number of pages in each book. I would like to have another custom column that shows the average number of words per page, so it would divide #words by #pages, provided both #words and #pages contain positive integer values. How might I achieve this?