How do we know what natural numbers are?
72420
Is $\mathbb{N}$ impossible to pin down?
158257
Is aleph-$0$ a natural number?
156242
As many even numbers as natural numbers.
28942
About Math notation: the set of the first $n$ natural numbers
73846
Tell Wolfram Alpha that a variable is a natural number
68976
Given real numbers: define integers?
11119
What are imaginary numbers?
24582
Is the set of sequences of natural numbers with trailing zeros countable?
138569
Is the “sum of all natural numbers” unique?
131708
Sum of powers of natural numbers
111938
How do I find a flaw in this false proof that $7n = 0$ for all natural numbers?
52682
Is the power set of the natural numbers countable?
110958
How to solve for any given natural number n?
156660
The set of all strictly increasing sequences of natural numbers
4530
For which natural numbers are $\phi(n)=2$?
22498
In set theory, how are real numbers represented as sets?
130149
Computablility of a real number