Brain Teaser Trouble

I am working on some brain teasers and having a horrible time trying to figure a few of them out. Anyone have any ideas about any of these?

2 = CI
8 = NMS
18 = CS
3 = DC
0 = NCC
16 = BPT
3 = HC

example of how these work is: 24 = HD (Hours Day)
18 = HGC (Holes Golf Course)

Please help....it is making me crazy that I can not figure it out