Guys and Girls Please Answer?

(I'm a 15 year old male)..And I was talking to a girl i like and got into this conversation about dating and other stuff. So she asked me how many girls have i been out with so i simply replied 3 and in that 3, the last one the girl cheated. So I asked her the same question and she said 15 and Thats where i got throwed off..is this even normal??? how can a girl be 14 and go with like 15 dudes? I'm staying away from her...I would put her down as a skank because to me its TOO many. I know adults that havent even had 15 boyfriends and girlfriends.