How many Senate are there and why?

Answer 1

According to the U.S. Constitution, each state elects two members to the U.S. Senate. So nowadays that means 50 states x 2 = 100.

Answer 2

Each state has two senators, which means that in the Senate there are 100 senators.

Answer 3

There is one U.S. Senate because that's what the U.S. Constitution requires.

Answer 4

100