In Saw 2, when Xavier was looking for the numbers on the people's backs why did he have to cut them?

Question

I mean, couldn't they all just have worked together? Tell each other the numbers?

Answer 1

Because Xavier isn't the type to work with people. He did throw whats-her-face in the pit of needles, and he cut his own number off his neck. He was just a violent criminal, and of course, it would have ruined the movie.  

Answer 2

But... But...that would ruin the movie!

Answer 3

haha my friend i wonder the same thing. The reason is because it was a gorry movie and that would ruin part of the movie and make it less scary. in other words....ratings my friend all due to ratings.

Answer 4

So he knows who he has looked at before.