Fin cutting

[heyzeus]

Hi, sorry if this sounds like a stupid question, but I have to be honest, I am a pretty stupid person- so I appreciate any help.
I'm about to start using Finpecia 1mg, bought from Inhouse, I want to start with, and maybe only ever take .25 twice weekly. So I cut it into 4 pieces right? I only ask because it seems very small. Is it a case of not the size of the dog in the fight but the size of the fight in the dog?
Also will other 3 cut pills still be effective after being exposed to the air for up to 2 weeks if I keep them sealed?
Thanks!