^^^ use whatever formula you want.
you will need another vial to put it in to store what you don't use in the fridge.
its math dude. come on. 5000iu's into 10cc's of bac water means for every 1 cc you get 500iu's of hcg. 5000iu's into 5cc's of bac water is 1000iu's per cc and so on.. this is easy math you can do in your head.
you are making this way too complicated than it is
dont use a slin pin to draw and mix either.. use a regular needle, will save you a lot of time and hassle.