0.999…

Illustrations in base 10

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  Explanation why "0.999..." equals "1" using number lines

Illustrations in other bases

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  Base 3: nested intervals
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  Base 3: 1/4, 2/3, and 1 in the Cantor set
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  Base 4: The decimal 0.333… = 1
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  Base 4: The 4-adic number …333 = −1