A math puzzle circulating online looks almost too easy: add 1000, 40, 1000, 30, 1000, 20, 1000, and 10 in your head. Most people confidently land on 5000. The correct answer is 4100 — and the reason so many get it wrong reveals something telling about how the brain handles numbers.
The puzzle and the step-by-step path to 4100
The sequence runs: 1000 + 40 + 1000 + 30 + 1000 + 20 + 1000 + 10. No calculator, no paper — only mental arithmetic. The constraint is deliberate: it pushes people to work fast rather than carefully.
