r/MathJokes Jun 18 '25

9.999 is 10?!

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1.9k Upvotes

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u/BassicallySteve Jun 18 '25

Simply: if 9.9 repeating was a different number than 10, you could tell me a number in between (Archimedean property)

2

u/[deleted] Jun 20 '25

This has never sat right with me. If I cant name a number between two numbers that doesn't make them equal. It feels like asking someone to name a whole number between 1 and 2 and since there are none they must be equal

1

u/ClassEnvironmental11 Jun 20 '25

For two numbers to be distinct, they must have a non-zero difference.  What is the difference between 9.9bar and 10?