Formula = Pitcher’s earned run average, multiply the total earned runs charged against his pitching by 9, and divide the result by the total number of innings he pitched.

So this is the standard MLB formula. My question is: In HS baseball there are 7 innings played. Our team got slaughtered and just stopped that game in the 5th inning. So for era do you still have to multiple the total earned runs charged by the pitcher BY 9? Shouldn’t it be out of 5 since there was only 5 innings played?

Im curious about this because I pitched like 1/3 of an inning that game and my coach multiplied my ER(3) by 9 innings played in a game. He used the standard MLB formula(which led to a bizarre era of 63.00). Shouldn’t the formula change based on how many innings are actually in the game?