work.

Can I work 40 hours a week and be Part time? 
I work as a cashier at target and they actually never mentioned if I'm part time or full time. But since they never brought up any benefits I'm guessing they put me as part time ? This week they have me at 40 hours and next week I'm doing 28 hours. Btw , they already trained me for about a week, Everyone gets trained 4 hours . I live in CA , getting paid every 2 weeks