It looks easy. That’s exactly why almost everyone gets it wrong.
40 ÷ 5 + 11 = ?
Nine out of ten people who try this in their head answer 27. They add 5 + 11 to get 16, then divide 40 by… wait, that doesn’t even work. Others answer 24, or 35. The real answer surprises almost everyone.
The answer is 19.
Here’s the trick: the order of operations. Division always comes before addition, so you must solve 40 ÷ 5 first. That gives you 8. Then add 11, and you get 19.
The people who get 27 are doing the addition first — a completely natural mistake, because our eyes read left to right and our brains want to group the numbers that sit next to each other.
Math teachers love this puzzle because it exposes one of the most common errors in mental arithmetic. And once you see it, you can’t unsee it.
Share it with someone who swears they’re good at math. Then watch them say 27.
