It's gotta be a power of two Maruyama. Something like 1024 or 16384.
In old games, though, and mechanical devices, it wasn't based on how much the data type could hold, but about how much could be displayed. If you have 4 slots, the most that could be displayed is 9999, and if you get to 10000, it instead displays 0000. Sometimes it still kept track of the true number because it still fit in the data type, and sometimes the developer would actually cut off the leading digit from the value, so that what could be shown was correct. But analog/purely mechanical devices would actually just lose the value.