1. A circular analog mathematical wall clock, with different mathematical formulas at each hour mark instead of traditional numbers. A unique and interesting way to track time! The big blackboard equations/figures on the black background are easy to read. The red second hand provides extra clarity. 2. Perfect gift for math lovers, university professors, math teachers, students, engineers and scientists. Ideal for classrooms, offices, study rooms, university dormitories, libraries, bedrooms, bathrooms or any room in your home or company. 3. Silent mechanical device without ticking, with sweeping function. Enjoy the quiet environment! The accurate Shi Ying movement guarantees the accurate time. 4. Strong plastic frame and glass lens make it easy to clean and keep dust away from the dial. Great Christmas/year-end gift or talk film! 5. Easy to hang. Powered by an AA battery-not included (Note: the positive electrode of the battery should be inserted first).