Personalized Pi Math Day grunge Toddler Long Sleeve T-Shirt. Pi Math Symbol Toddler Long Sleeve Tee - Black has fun grunge look. graphic licensed from and c. www.graphicsfactory.com A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.