Personalized Happy Pi Day Pink Math Symbol Women's V-Neck T-Shirt. Cute pink pi math symbol with stitch border on a Women's V-Neck T-Shirt - Black with Happy Pi Day quote. 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