136
What is 2?
(lemmy.blahaj.zone)
Context:
In ZFC set theory (which most of modern maths is built upon). The natural numbers are defined as recursions of empty sets.
Ie. 0 = ∅ (the empty set)
1 = {∅} = {0}
2 = {∅, {∅}} etc…
0 is the empty set.
1 is the set containing only 0.
2 is the set containing only 1 and 0.