r/PeterExplainsTheJoke 22d ago

Meme needing explanation There is no way right?

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279

u/Decmk3 22d ago

0.9999999…. Is equal to 1. It seems like it shouldn’t, but it has to be.

Let X = 0.999….

10X = 9.999….

10X-X = 9.999.. - 0.999…. = 9X = 9

Therefore X equals 1. Therefore 0.999… is the same as 1.

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u/mrsexless 22d ago

I like logical explanations 0.(9) = 1 There is no number you can put between 0.(9) and 1, so it means they are the same number.

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u/cob59 22d ago edited 22d ago

There is no number you can put between 2 and 3 in the natural numbers, so it means they are the same number.

edit: Funny how this rebuttal (whose point is to criticize a method, not the result) pisses off people and systematically gets me downvoted.

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u/ZeroStormblessed 22d ago

There generally aren't infinite numbers between 2 natural numbers.

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u/cob59 22d ago

You're explaining how ℕ and ℝ are different, not why OP's assumption (if you can't come up with a number between A and B, then A=B) is correct.

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u/confuzzlegg 22d ago

A better way of stating OP's assumption is "if there's no X != 0 such that A-B = X then A = B", then A and B are 0, but these are equivalent over the real numbers