One Rule, Same Answer

PEMDAS — parentheses, exponents, multiplication/division, addition/subtraction — gives every reader a single path through an expression. Run the steps in order and the answer is repeatable: change someone's formula and they can retrace exactly where it goes. Break the order and the trail goes cold. That repeatability, not the mnemonic itself, is the whole point.

A quick habit makes all of this stick: read left to right, but jump to the highest-rank operation you can see first. Scan for parentheses, then exponents, then any multiplication or division, then addition or subtraction — handling each level fully before dropping to the next. Saying the level out loud as you go ("parentheses... exponent... now multiply") catches the slip before it reaches your answer.