What does ∩ mean in math?

∩ The symbol ∩ means intersection. Given two sets S and T, S ∩ T is used to denote the set {x|x ∈ S and x ∈ T}. For example {1,2,3}∩{3,4,5} = {3}. \ The symbol \ means remove from a set.

What does a ∪ B mean?

The symbol ∪ is employed to denote the union of two sets. Thus, the set A ∪ B—read “A union B” or “the union of A and B”—is defined as the set that consists of all elements belonging to either set A or set B (or both).