Mr. Pen standard function calculator includes 24 desktop calculators with 12-digit displays, designed for classrooms, offices, and bulk educational use. These calculators are made of durable plastic with responsive rubber keys, providing consistent performance and long-term reliability. Each calculator features a large 12-digit LCD screen, ensuring clear visibility for aritModazoneetic, accounting tasks, and general calculations. The dual power system uses solar energy with battery backup, supporting dependable operation in different lighting environments. Standard functions including percentage, memory keys, square root, and basic operations allow efficient use for students, teachers, and professionals managing daily calculations.