Here is a 3-paragraph summary of the blog post for mathopen.com:
This blog post opens with a clever puzzle that was included as part of an entrance test for a STEP mathematics program. The puzzle asks: "What word would you use to describe a man who does not have all his fingers on one hand?" Out of 17 questions on the test, this was the only trick question, and it was placed there with a specific purpose in mind.
The trick, of course, is that the answer is "normal." Most people have their fingers spread across two hands, so a man without all his fingers on one hand is perfectly ordinary. The puzzle is designed to catch people who immediately assume the question is asking about someone with a disability or missing fingers, revealing how quickly we can misread a problem when we bring our own assumptions to it.
The deeper lesson here is one that applies directly to mathematics: reading carefully and questioning your assumptions are just as important as raw problem-solving ability. The instructor used this puzzle to assess whether students could resist jumping to conclusions and instead think critically about what is actually being asked. It is a lighthearted but genuinely insightful reminder that in math, as in life, the framing of a question matters enormously.