What's a (natural) number? What does it look like?
We represent numbers with symbols like 1, 2, 3, I, II, III. We are aware of objects that have a numeric property: A square has 4 sides.
But, what about the number itself? What is it? What does it look like?
In 1923, John von Neumann proposed a set-theoretic construction of natural numbers: We can start with the empty set, and then define the next number as the set containing all previous numbers:
0 = {}
1 = { {} }
2 = {0, 1} = { {}, {{}} },
3 = {0, 1, 2} = { {}, {{}}, { {}, {{}} } }
And so on.
"Number 10, Console", is a variation of "Number 10, Red", inspired by von Neumann's construction.
Each closed shape corresponds to a set.
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