∑ "is a symbol in mathematics. Pronunciation is "belonging". If a∈A, then A belongs to set A, and A is an element in set A. ..

Basic meaning

We usually use uppercase Latin letters A, B, C, … to represent the set, and lowercase Latin letters A, B, C, … to represent the elements in the set.

If a is an element of set A, it is said that A belongs to set A, marked as A ∈ A; If a is not an element in set a, it is said that a does not belong to set a, and it is recorded as a? (∈ slash, similar to = and ≦) A.

For example, if we use a to represent the set of "all prime numbers in 1~20", there is 3 ∈ a.

When reading this symbol in mathematics, you can directly use the word "belonging" to express it.

For example, a∈A can be read as: small A belongs to big A.