Adele's four album titles so far (19, 21, 25, and 30) have all been numbers. (In fact, they've been her ages.)

For this market, the title of Adele's next album of new music must exclusively be a number (no other words or symbols), unless it's a number with a subtitle (which counts).

I'll keep the market open until she announces another album of new music.

General policy for my markets: In the rare event of a conflict between my resolution criteria and the agreed-upon common-sense spirit of the market, I may resolve it according to the market's spirit or N/A, probably after discussion.