This leads people to treat it as multiplication "M", but it's expanding brackets, "B", so must be done first! See meme. Lastly (for this week) note in our previous screenshot "number or a letter". By "letter" they mean pronumeral. "pro" means "substituted for" so it's literally a symbol (letter in this case) substituted for a numeral. What I'm getting at is THEY ARE THE SAME THING. Mistake #3 "that rule only applies to letters". No, it applies to letters AND numbers. Continued next week...