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The first sentence before “use water” is still stumping most students at Keith Devlin’s Coursera course Introduction to Mathematical Thinking.
Even when the answer is posted in discussion threads by some and the above image search in a thread marked that way, they still can’t find it or just pass over it.
This is because people are more interested in themselves than the answer? They want to give their answer or their comment. So they just pass over the right answer or a link to an extensive discussion or even an image that clarifies it instantly.