As the original article notes, “The phrase ‘just your mind’ makes people skip the only method that works: one step at a time.” The instruction that seems to make the puzzle harder is, in practice, the instruction that causes the error.
Slowing down
treating each addition as a separate, deliberate step rather than scanning the sequence for a pattern — is the only reliable way to reach the correct total.
4100: what to remember the next time this puzzle appears
The puzzle continues to circulate online precisely because the wrong answer feels so convincing. The confident response of 5000 is the natural product of a brain doing what it is built to do — find patterns and arrive at round numbers quickly.
The fix is simple in principle and harder in practice: add every number in the order it appears, without skipping or grouping by instinct. The four thousands total 4000; the four smaller numbers total 100; the answer is 4100.
