A ruler with inches, centimeters, millimeters, and basic calculator functions all in one? Yes! With this fantastic Black Ruler Calculator, you can geek out over numbers and be super precise about your measurements down to the very last mm. It also makes a unique gift for your math-loving bestie, your science-nut sister, or someone else whose name just popped into your head. Made from ABS plastic, this Ruler Calculator measures 12-inches long. It features a 10-digit display and an on/off button and requires 1x "LR44" battery, included. Also available in white (sold separately).