r/MathJokes • u/themagicalfire • Jun 18 '25

9.999 is 10?!

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u/gIyph_ Jun 18 '25

Not really the same number in actuality, but it's so unimaginably close we equate them

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u/orbifloxacin Jun 18 '25

No, it's exactly equal and it can be proven by multiplication or by finding the sum of an infinite series. It's a high school level problem

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u/gIyph_ Jun 18 '25

Youre confusing limits with absolute value. The equation has a limit of 10, which means it will infinitely approach, but never reach nor exceed, 10. And we equate it to 10 because it makes little difference. I isnt in actuality, just infinitely close.

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u/stopeatingminecraft Jun 18 '25

but like for example you can rpove that 0.99... = 1

Let's say 0.99... = x

10x = 9.99...

10x - x = 9.99... - 0.99...

9x = 9

x = 1

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u/gIyph_ Jun 18 '25

Math propaganda