Abstract: A small-sized electronic calculator, which comprises a power source in the form of a solar battery having a film of polycrystalline photoconductive material, such as selenium. The solar battery is connected for angular movement to the calculator body by suitable connection means, such as a hinge and a foldable metal spring. The calculator body includes a display section of liquid crystal elements. The solar battery may include an overvoltage preventing circuit and a reset switch. The output of the solar battery may be converted to a digital value to indicate the luminescent by the display section.