You probably know that there are some real number nuts in the Military Payment Certificate (MPC) collecting community. One popular (crazy?) approach is to collect MPCs only one position on a sheet. The smallest sheet had 50 positions so you can imagine how much harder it is to find pieces from the desired position rather than just to find the item by type.

Off the top of my head, collectors are building sets from the following positions: 1, 2, 3, 4, 7, 8, 11, 13, 22, 23, and 39. I probably forgot some. I think that Joe Boling needs only two pieces to complete his 90 piece collection of positions eight. He has a cute story of how he got started on this task. Perhaps he will tell it here.

A really interesting variation is to collect the notes from the position that corresponds to the note's denomination (there are at least two of those sets in progress).

The ultimate collection (so far) along these lines is Larry Smulczenski's. His Number is 39. Of course he collects MPC from that position, but he collects other things with 39. He loves serial number 39. They are hard to find on MPC, so he finds others. If he cannot find serial number 39, well, 3900, 39000, 3939, 393939, 390039 and any other variation will do. When the first class postal rate was 39 cents, he collected all of those stamps. Can anyone figure out why he collects this particular number?