[Closed] Stem angles? low to high and stem length

I have decided to jack the front end up on my 26inch wheeled MTB. I ordered a 100mm stem with 17d rise. Am I correct in that the normal 5-6d rise stems that most bikes seem to have on them are longer in the same length of stem in say a 20d rise stem would be> What I mean is the actual higer angle of the stem being higher, moving the bars foward is it not? Well on comparing a few stems I had I did notice that the 100mm 17d stem was actually only as long as my 90mm with the low angle of 5d. Would I need a longer stem to make up for the higher angle. Say if I liked 100mm stem but wanted a lot more angel to higer it up would I say go for a 120mm?