DUAL SOLAR POWER AND BATTERYSolar power and battery can both keep the calculator running (AAA battery NOT included).The solar calculator has auto power off. < p>12 DIGIT CALCULATOR12 digits can operate the financial calculator for large calculations. Suitable for businessmen, workers, teachers, students, or anyone who needs to do calculations. SENSITIVE LARGE BUTTONDesktop calculators adopt scientific compliant large button design to the use of human habits and comfortable to touch. 4 Non-slip Mats The big key calculator with 4 non-slip mats, which can prevent slipping during use and not damage desks.< /p> NOTEThe Accounting Calculator screen may be difficult to read when using it in low light conditions without a battery. Please insert a AAA battery if you need to use it in low light conditions.