Electronic calculator providing flexible constant utilization

An electronic calculator comprising a keyboard having numerical keys and others, output means, a read only memory (ROM) to store control programs, a random-access memory (RAM), and a CPU to control these devices, wherein said RAM provides a constant register to store constants, an operator storage unit to store operators, and a flag storage unit to store a flag to show whether an operator is positioned before or after a constant, wherein said keyboard includes a setting key to set an entered constant and operator and includes also a confirmation key which initiates operation of said output means to generate characters confirming the order of entry of the predetermined constant and operator, wherein, according to the contents of the flag storage unit in RAM indicative of the position of the operator, the sequence of subsequent calculations employing the constant and operator is changed.