A seemingly simple arithmetic problem shared on social media has divided users and reignited debate over the order of operations.
An X post that asked followers to calculate 70 + 30 ÷ 2 x 3 and challenged them to solve it in 20 seconds or less drew hundreds of replies offering a range of answers. Some respondents gave 150 or 25, while others said 115. The correct result, under standard order-of-operations rules, is 115.
The problem was shared by X user @BholanthDutta and relayed in a Daily Mail story by Sophie Gable. It prompted discussion about the mnemonic for remembering operation order — commonly taught as PEMDAS (parentheses, exponents, multiplication and division, addition and subtraction) — and how people apply it.
Applying the conventional rules yields 115. There are no parentheses or exponents in the expression, so multiplication and division come before addition and subtraction. Because multiplication and division are of equal precedence, they are carried out left to right: first 30 ÷ 2 equals 15, then 15 x 3 equals 45, and finally 70 + 45 equals 115.
Some incorrect answers stemmed from treating multiplication as universally prior to division or from simply performing operations strictly left to right without respecting the equal precedence of multiplication and division. Others appear to have made arithmetic mistakes while trying to respond quickly.
The exchange is part of a broader pattern of short, shareable puzzles that circulate on social platforms to test quick recall of school-taught rules. Such puzzles often provoke debate not because the mathematics is ambiguous, but because memories of procedural steps fade when they are not regularly practiced.
Educators and math communicators have previously noted that different mnemonics and regional teaching variations can contribute to confusion. While PEMDAS is widely used in the United States, other mnemonics like BEDMAS or BODMAS emphasize brackets and orders and can lead to the same answer when rules about left-to-right evaluation for equal-precedence operations are followed.
The post drew comments from users who said they solved the problem in under 20 seconds, and from those who said it had tripped them up. The exchange underlines how a short, familiar exercise can produce widespread debate when participants rely on recollection rather than methodical application of rules.