Is $\mathbb{R}\setminus\mathbb{Q}$ countable?
18360
Proof that the irrational numbers are uncountable
3296
Proof That $\mathbb{R} \setminus \mathbb{Q}$ Is Not an $F_{\sigma}$ Set
16507
Is $\mathbb{Z}= \{\dots -3, -2, -1, 0 ,1 ,2 , 3, \dots \}$ countable?
27188
Bijection between $\mathbb{R}$ and $\mathbb{R}/\mathbb{Q}$
115004
If $x\notin\mathbb Q$, then $\left|x-\frac{p}{q}\right|<\frac{1}{q^2}$ for infinitely many $\frac{p}{q}$?
124060
Are these subsets of the powerset P(N) countable?
54496
Showing that $\mathbb{R}$ and $\mathbb{R}\backslash\mathbb{Q}$ are equinumerous using Cantor-Bernstein
76240
How is $\epsilon_0$ countable?
128437
How to prove that a finite set is countable
99656
Prove that the set of all algebraic numbers is countable
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?
1591
What does $\mathbb{R} \setminus S$ mean?
68139
Show that the set of polynomials with rational coefficients is countable.
41192
Neatest proof that set of finite subsets is countable?
25795
Density of $\mathbb{Q}^n$ in $\mathbb{R}^n$
63276
Is an arbitrary union of a chain of countable sets countable?
17525
Why the interior of $\mathbb{Q}$ in $\mathbb{R}$ is empty?