Help please. i wanna ask him. answers greatly appreciated?

ok so i like this guy. ive known him since 1st grade, we went to different middle schools and now we are at the same high school. he is in my cl and i sit right next to him. ive been getting mixed signals from him because one day he will be really talkative to me and the next he wont. i guess you could say im confused. anyway i wanna get his number because if we text a little i guess i could see how he feels about me. how do i ask him for his number very subtly. help please. answers GREATLY appreciated. thanks.