If A is a countable set, how can I show that A has countably many finite subsets?
41192
Neatest proof that set of finite subsets is countable?
93419
Let $\mathcal A$ be a collection of pairwise disjoint subsets of a $\sigma$-finite measure space,Show that $\mathcal A$ is at most countable.
16413
Proving existence of surjective $f:\mathbb{N} \rightarrow A$ implies $A$ is at most countable.
95747
Number of countable subsets of $\mathbb{R}$
63678
Let $A$ and $B$ be countable sets. Is there any function $f$ such that a certain condition holds for an uncountable number of functions $g$?
7678
Show "countable complement topology" is a topology
120273
Showing that a collection of sets is a $\sigma$-algebra: either set or complement is countable
102543
Real definition of "countable set"
136006
Prove that any countable cartesian product of countable sets is countable
70143
Mutually exclusive countable subsets of a countable set
91237
Every infinite set contains a countable subset
42794
Prove that functions map countable sets to countable sets
138768
Showing that the family of Borel sets is countably generated
33157
Proof that an infinite subset of $\mathbb{N}$ is countable
99599
Uncountable and countable
127362
How do I prove that there doesn't exist a set whose power set is countable?
75019
Infinite Cartesian product of countable sets is uncountable