MATERIAL - This analog wall clock is made of acrylic material with white letters and numbers, ideal for classrooms or offices. Special Design - The black dial is designed to look like a blackboard, with each mathematical equation painted to look like white chalk. Instead of traditional numbers, this wall clock has a different equation for each mark. Fun Math - The hand moves around the dial to indicate the time of day through a different mathematical problem for each hour. A unique and creative way to keep track of time, this wall clock is a fun and challenging brain teaser. If you can read this clock, you are undoubtedly a math enthusiast. Each hour is marked by a simple mathematical problem. Solve it and solve the riddle of time. Ideal for the aspiring math student or for anyone who wants something different in a clock. Usage - Perfect for the aspiring math student or anyone who wants something different in a clock. For classrooms, study rooms, living rooms, nurseries, offices. Note: Regarding the battery, the battery is not included, please use the carbon-zinc battery, do not use the rechargeable battery or other batteries, due to the high output current of these batteries, the accuracy of the clock may be affected. Specifications: Material: Acrylic Color: Black Shape: Round Size: 30 x 30 / 11.8 x 11.8 inches Power: 1 AA battery (not included) Unique appearance and good performance, looks modern and shows accurate time. The clock measures 11.8 inches in diameter, it is easy to see from a distance. A unique and creative way to keep track of time, this wall clock is a fun and challenging brain teaser. Each hour marked by a simple mathematical equation can overcome your fear simply by solving some simple mathematical problems with each corresponding hour. Great gift idea. Give one of these wall clocks to a math teacher, engineer, mathematician, or anyone who loves straight numbers. A very modern decoration for the wall, especially for the classroom, office and study, as well as an ideal gift for your friends or their children. Package includes: 1 * Mathematical wall clock