🦭 Number Sets (ℕ, ℤ, ℚ, ℝ)

Test your skills on number sets, membership, operations, classification (ℕ, ℤ, ℚ, ℝ, ℂ), and positive/negative subsets.

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Learning Topics

Frequently Asked Questions

What is a set and what are its elements?

A set is a collection of distinct objects or numbers called elements. We write a set by listing its elements inside curly braces, like A = {1, 2, 3}.

What do the symbols ∈ and ∉ mean?

The symbol ∈ means “belongs to” or “is an element of” (e.g. 2 ∈ {1, 2, 3} is true). The symbol ∉ means “does not belong to” (e.g. 4 ∉ {1, 2, 3} is true).

How do I check if an element belongs to a set?

Simply look at the list inside the curly braces. If the element appears in that list, it belongs (∈). If it does not appear, it does not belong (∉).