NFHS Rules.
Star running back #31 has his jersey ripped after piling up 75 yards in the first half. Coming onto the field at the start of the second half he goes, "Ref, I changed jerseys, mine was ripped, I'm wearing number 24."

What is the rule?

Do you inform the opposing coach or let him discover for on his own?

I don't think there is a rule that requires you to notify the opposing coach but I probably would. But my guess is the first time he rips off a 20 yard run, he'll know! :^)

First he does not need to inform us. Second, it is not our responsibility to inform anyone.

>shawn.wortman: First he does not need to inform us. Second, it is not our responsibility to inform anyone

I am not sure of the rules for four-down ball, but in three-down (Canadian) the book is rather clear that changes in numbers should be reported to a game commissioner... not sure of the existence of such a beast in four-down ball.

However, I point out that there may be times when knowing who is in what jersey matters a lot.... such as if one player has a medical condition or the like.