How to let a guy know you're not interested?

this guy Ive never met or talked to added me on fb but we go to the same school. he's a senior I'm a sophmore and he wanted my number so I gave it to em and I'm kinda getting the hit he just likes me cuz he didn't even know me. well he texts me alot and I don't like him at all I just am not attracted to him. so wen he txts me I always do short messages like "yea" "lol" & "cool" and sometimes I just dot reply. do I jut keep not replying then will he get the hint?