I have just exchanged emails with Charles Parsons, asking him for some guidance about the evolution of the philosophy of mathematics after Kant [a subject of which he is a widely acknowledged master.] It brought to mind the Kant study group that the two of us ran sixty years ago in our graduate apartment every Wednesday evening from eight to midnight -- the single greatest educational experience of my life, after C. I. Lewis' immortal Kant Course. Over the course of the year, we worked our way through the First Critique and even tackled the mysterious Third Critique.
Kant introduces subsection numberings into the revised version of the Deduction in the Second Edition -- twenty-seven in all. Now, as it happens, if you look at the Table of Functions of Unity in Judgment, you will see that combining and permuting the triads of Quantity, Quality, and Modality, there are 3 x 3 x 3 or 27 possible combinations -- for example, a universal affirmative assertoric judgment, or a particular negative apodeictic judgment, etc.
One of our little group, the inspired Sam Todes, who passed away far too early [and from whom I bought my very first car, for $100], got into his head the manically brilliant idea that each of the 27 sections of the Deduction in B was intended by Kant to exemplify one of those 27 judgment types. I thought he was crazy, and we had an uproarious argument until we all collapsed in laughter.
That is what graduate study was supposed to be!