Degree of unsaturation why is it 5?

Question

C20H32CIN
do i ignore the second C?
because i did
21(2)+2=44 44-32+1-1 / 2 = 6
but i get it right with
20(2)+2=42 42-32-1+1 / 2 = 5
do i always ignore extra C's?

Answer 1

No, you don't ignore a second C; all should be counted. I don't think that is a C. I think it is a Cl (chlorine).
So you have
20C
32H
1Cl
1N which gives you
[2+2(20)-32+1-1]/2 = 5
Viola!

Answer 2

you're right! sorry i guess im just tired from over studying that i saw the wrong letter!