Personalized Happy Pi Day Robot Math Class Women's V-Neck T-Shirt. Pi Day Women's V-Neck T-Shirt - White has funny vintage style robot and math symbol Happy Pi Day celebration logo. 5.0 oz., 100% pre-shrunk cotton Athletic Heather is 90/10 cotton/polyester 1x1 rib collar with mitered v-neck Shoulder-to-shoulder taping Ladies' fit