Simon Stead
Jul 21, 2017 · 1 min read

Why 0.999… = 1 is one of my favourite facts in mathematics, because you can introduce a lot of concepts, confuse and enlighten people at the same time.

I love these explanations, but one of the simplest ways I found to explain this to children was to talk about the density of the reals.

Something like…

Q “What makes two numbers different? Give me an example”

A “23 and 26 are clearly different because 25 is between them. 23 and 23 are the same number because there’s no number between them.”

Q “So take 0.999… and 1, what number separates those?”

A “…”

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Simon Stead

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Freelance creative technologist & polymath.