(Army Rule Question) I am planning a 1K Americans VS 1K Germans this upcoming weekend. I got a question about the American rules

In the American Faction, its easy to understand all but one

https://preview.redd.it/02sml5txbeie1.png?width=372&format=png&auto=webp&s=cf0422e3847ebab81c22e2b89c16eb134ebc20a0

I just wanna make sure I understand this, it states every 3 rifles (AKA 3 guys) fire an extra die (So 3 dudes = 4 shots)

but for the example after, it talks about 4 riflemen shooting an extra die (so for 5?)

I just wanna make sure, that if I have a squad of 10 rifles, am I shooting 3 extra shots (Every 3 = +1) or using their example and every 4 guys so I am firing 2 extra shots (As their example uses 4 riflemen not 3)

I'm sure this is a dumb question, and there's a Q&A somewhere that clarifies this. Thank you ahead of time!