Are these correct?
He has six-pack abs.
He has 6-pack abs.
He has a six-pack.
He has a 6-pack.

(Many people)
They have six-pack abs
They have 6-pack abs.
They have six-packs.
They have 6-packs.

Are these all correct?

Question

Are these correct?
He has six-pack abs.
He has 6-pack abs.
He has a six-pack.
He has a 6-pack.

(Many people) 
They have six-pack abs
They have 6-pack abs.
They have six-packs.
They have 6-packs.

Are these all correct?

Answer

I have seen and heard all of these variations. I would say they're all correct.

Answer

Hello Tyker!
According to the Collins Dictionary it should be written like this: "six-pack" and this term has two meanings  
 so the sentence should show the context. So the correct way of writing it is: "He has a six-pack stomach." or  "He has six-pack abs." and "They have six-pack abs."  
I hope that helps!

Answer

All doog.
BTW: He has a six-pack, without context probably means he's carrying beer.

집에서 편안하게 언어를 배울 수 있는 기회를 놓치지 마세요. 경험 많은 강사진을 살펴보고 지금 바로 첫 수업을 신청하세요!