Personalized Happy Pi Day Girls Toddler T-Shirt. Pi Day math Toddler T-Shirt - Heather and Royal with cute flowered border for a little math girl. A toddler-soft cotton tee in look-at-me, big kid colors. 4.5 oz., 100% combed ringspun cotton. White is sewn with 100% cotton thread. Topstitched rib crew neck. Double-needle stitched sleeves and bottom hem. Shoulder-to-shoulder taping.