When you see 2+3×4, which operation happens first? Without rules, you might get different answers.
PEMDAS (or BODMAS) tells you the order: Parentheses, Exponents, Multiplication/Division (left to right), Addition/Subtraction (left to right). So 2+3×4=2+12=14, not 20.
Computers follow these rules exactly. If your code computes the wrong value, check your parentheses. One misplaced bracket changes everything.