From Sonic Retro
First appearing in Wii U/PC version of Sonic Lost World and work the same throughout all the games they are in. The Number Rings sets appear within a determined area of a Zone or level with focus either on running, platforming or Parkour (in case of Sonic Lost World) sections of said level. They must be collected sequentially in a numerical order, if collected in the wrong order they will immediately disappear.
Particular to Sonic Lost World, collecting all of them will reward the player with an extra life.
Aside from unlocking the Silver Moon Rings, collecting the Number Rings serves no benefit other than extra bonus points as well as achievements/trophies in the PlayStation 4, Xbox One and Steam versions of the Sonic Forces and the completion of a mission in certain Cyber Space levels present in The Final Horizon update for Sonic Frontiers.