A calculator is an electronic machine invented by modern people that can perform digital operations. Generally consists of operator, controller, memory, keyboard, display, power supply and some optional peripheral equipment and electronic accessories, by manual or machine equipment. Teencher Inspection team consists of professional quality control and international trade experts, each member with extensive inspection experience and very strong sense of service. our inspection can help you to reduce logistics costs, return risk, complaints, compensation and potential brand reputation due to quality problems.