Celebrate an 11th birthday in style with this unique black t-shirt! The design features a cool math-themed graphic, including formulas and equations surrounding a large square root of 121, making this the perfect gift for a budding mathematician or anyone who loves numbers. The phrase "Years Old" is prominently displayed beneath the root, adding to the fun. Made from a soft, comfortable fabric, this t-shirt is great for everyday wear, birthday parties, or even math class. This fun t-shirt is sure to make the birthday boy or girl feel special and smart on their big day. Great for casual wear and parties.