Sprite Replacement: Moniter number

I'm making a mod and I am going to replace the moniters but I don't know wich number the scrambled moniter number is.

What I did whenever there was a sprite I need to replace but I didn't know the number was to copy srb2.srb and rename the copied file to xxxx.wad with xxx being whatever the heck you want to name the file. From there, it can be opened in SlumpEd, XWE or whatever you use for editing wads.

I looked in there but I did not find the name of the moniter where it's picture is scrambled