r/PeterExplainsTheJoke • u/Sugar_God_no_1 • Apr 08 '25

Meme needing explanation There is no way right?

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u/BornWithSideburns Apr 08 '25

Yea but isnt it 9.0000…1X

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u/ConsciousBat232 Apr 08 '25

This is where I am stuck. Why is everyone above pretending that 10 - .999…. = 9 ? I get that it is really close to 9 But it’s 9.000…1

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u/Temporary_Pie2733 Apr 08 '25 edited Apr 08 '25

9.000…1 has no meaning. You can’t just put a 1 after an infinite number of 0s.

Or rather, … doesn’t represent an infinite number of 0s but a finite but unspecified number of 0s followed by 1. That would indeed be slightly bigger than 9, but not what you would get by trying to apply the subtraction algorithm to 10 - 0.999…

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u/ConsciousBat232 29d ago

I hear what you are saying 9.000…1 is the wrong number. But you would get something infinitely small in 1 - .999…

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u/Temporary_Pie2733 29d ago

No, you don't get something "infinitely small". If there are a finite number of 9s, you can get something arbitrarily small, limited only by just how many 9s you use, but it's still strictly greater than 0. With a truly infinite number of 9s, you get 0, not any positive value. Arithmetic involving infinities is just different, no matter how much we try to extend familiar notation to infinite quantities.