What's your favourite paradox?

[Arkten]

I have a few;

This is just something to make one think: 0.999... (0.9 recurring) = 1. Do you agree?

Did this recently as an addition to one of the topics I'm studying:
If 0.999... = x
9.999... = 10x
10x - x  would give (9.999... - 0.999...) 9.
9x = 9 so x = 1.

IT IS JUST A THEORY...

Well, first of, multiplying something by ten always requires the number to end with a zero, (this does not matter for now as you see in the example, just wanted to point that out)
If 0.999... = x
then 10x = 9.999...0 <- This zero is meaningless as it stands behind a comma
so 10x - x would result in (9.999...0 - 0.999... = 9)
9x = 9 so x = 1

But, doesnt multiplying by ten also mean that moving its content forward by one decimal? Meaning that,
10x = 9.999...0 <- On this xth position (the theoritically last position of this not ending number) is a zero
01x = 0.999...9 <- On the same position (the theoritically last position of this not ending number) must be a nine
so 10x - x would result in (9.999...0 - 0,999...9 = 8,999...1)
9x = 8,999...1 so x = 0,999...9

These are my thoughts about this topic, this is pure theory.