Companies often include their stock or catalog number on a game, whether on the cover, an apron, the rules, a game board, or elsewhere. These numbers are also often included in company catalogs that list and generally also illustrate games available to retailers and individual customers. Sometimes they appear just as a number, e.g. “155” on Russell Mfg.’s Pan-Cake Tiddly-Winks from the 1920s, while others may be preceded by “No.”; for example “No. 85” for Rosebud Art Company’s Big Apple game.

In some cases (for example, Parker Brothers), the catalogs include catalog numbers for each game, but those catalog numbers often don’t appear on the game itself.

While generally a company will adopt unique numbers and not reuse them, there are exceptions. Milton Bradley was particularly notorious for reusing catalog numbers. Nearly all Milton Bradley games through the 1980s are marked with catalog numbers starting with the number “4”. Catalog number 4235 was used for Bean Bag in 1937 and Captain Video: An Exciting Space Game in 1952.

Occasionally, a company will append a letter after a catalog number that denotes either a revision to the item (e.g., rules) or a specific part of a game (e.g., a game board may have one suffix letter while the rules may have a different one).

On rare occasions, you’ll find a game that has different catalog numbers on different parts (e.g., cover, game board, rules). For example, McLoughlin Bros.’ The Jolly Tiddledy Wink Target Game is marked 853 on the cover and 857 on the rules.

In the 1950s and 1960s, some companies included a recommended retail price to the right of the catalog number on a game, leading some to believe it is part of the catalog number. For example, the marking on Transogram’s Electromatic Dial Quiz game from 1961, “3887 – 298”, indicates catalog number 3887 and recommended retail price of $2.98.

Starting mostly in the 1980s (though potentially as early as 1972), Universal Product Code (UPC) scan codes were printed on the outside of games for use in automatically registering the price of an item at stores during checkout. Sometimes the UPC numbers supplement the company’s catalog number, though in other cases, companies only print UPC numbers on their games.