I was looking at a dessert recipe and found this sentence:
Makes 24, 2" x 2" squares.
Almost every source I've found seems to suggest that "24" and "2 x 2" are cumulative adjectives (i.e. it doesn't make sense to replace the comma with "and"), so the comma is extraneous. However, you could make an argument that the added comma is correct because it adds clarity to a potentially confusing sentence.
My question is this: is there a specific grammar rule that allows you to write commas between numerals for clarity? Alternatively, is there another reason why this comma placement is correct?