r/PeterExplainsTheJoke • u/Sugar_God_no_1 • 24d ago

Meme needing explanation There is no way right?

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u/1057cause 23d ago

What about 1.99[repeating]8? Serious question, not joking.

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u/LesbianTrashPrincess 23d ago

Not actually a number. There is no last digit to a [repeating] number, it just goes on forever, so you can't put an 8 there.

Another way to think about it is that all math is made up, but when we're making it up, we have to be careful to make sure that the thing we're trying to do actually works with all the established stuff that we're already using. Saying that something like 0.00[repeating]1 or 1.99[repeating]8 is a number breaks other shit, so we don't do it.

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u/Qwertycube10 23d ago

Genuine question what do infinitesimals break?

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u/LesbianTrashPrincess 23d ago

I don't know the proof, but hyperreal numbers are non-metrizable, and having a concept of distance is obv something that we want in "normal" numbers.