# Math Help - Order of a group

1. ## Order of a group

What is the order of the group U(12)?

What does U(12) look like excatly?

Thanks.

2. Originally Posted by tttcomrader
What is the order of the group U(12)?
What does it means U(12)? Does it mean the primitive roots of unity of 12?

3. I really dont know, let me ask the professor tomorrow.

4. I just talked to my professor and he told me that U(12) is a group under multiplication modulo 12, so all k less than 12 such that k is relative prime to 12. Thus U(12) = {1,7,9,11}, so <U(12)> = 4.

Thanks.