0.999....=1

[Teeqoz]

Peh said:

Teeqoz said:

Nearly every single mathematical proof there is starts with stating something equivalent to "if x = 0.999... then:". If that is a valid reason to say my proof is invalid, then oh boy, we have to throw a lot of mathematics out the window! Also, the user I quoted was asking about the fraction proof, where I didn't use x at all.

Well then, what definition has 0.9999... ? What kind of number is that and what rules does it have?

Because 0.999...=1, 0.999.... has the same properties and rules as 1.

2*0.999...=2, just like 2*1=2.