If numbers be used to designate classes, there can be derived from a conjunct of classes numbers corresponding to the expanded product classes.

For example, let the product classes ābc and āb be designated by numbers I and 5 as in the following matrix:

By using 1 (20) instead of a, 2 (21) instead of b, 4 (22) instead of c, etc., the following relationship emerges between the designation of the conjunct of classes (take 12) and the product classes (I and 5): the product class(es) of any conjunct of classes is (are) (1) the sum of any negated class numbers and (2) seven less the sum of any unnegated class numbers.