Show off your love for math and celebrate a 13th birthday with this unique graphic t-shirt. The black tee features a variety of colorful mathematical equations, shapes, and symbols, centered around the square root of 169 (which equals 13). Below the math equations, 'Years Old' is printed in bold white letters. Made from a soft and comfortable fabric, this shirt is perfect for casual wear, birthday parties, or math enthusiasts. Grab this fun and geeky t-shirt for a quirky and stylish look!