Viral math puzzle highlights PEMDAS rule for order of operations

A viral post on X this week spotlighted a simple arithmetic puzzle and the rule that governs order of operations, PEMDAS.

Readers were asked to evaluate 6+7-3÷2 according to PEMDAS, which prescribes solving division before addition and subtraction. Using the rule: 3÷2 = 1.5; then 6+7 = 13; finally 13 − 1.5 = 11.5. A common misstep is to perform operations from left to right, yielding 5: 6+7 = 13; 13 − 3 = 10; 10 ÷ 2 = 5.

The sequence demonstrates the core rule: in any combined expression, parentheses first, then exponents, then multiplication and division from left to right, and finally addition and subtraction from left to right. The acronym is widely taught in schools, but several readers in the viral thread reported forgetting or confusing the rule, underscoring ongoing challenges in numeracy education.

In practice, PEMDAS means multiplication and division share the same level of priority and are resolved left to right, as do addition and subtraction. When applied correctly, the division 3÷2 is resolved before the addition and subtraction, which is why the calculation resolves to 11.5 rather than 5.

Educational experts say such puzzles can serve as a refresher for adults and a reminder for students that the sequence is not arbitrary. While the rule is simple in theory, applying it to everyday calculations can still trip people up, making these viral math quizzes a useful teaching moment. This piece aligns with the Science & Space category, where math cognition is a frequent subject of study, including how people learn and apply order-of-operations rules in real time.