Here's how to calculate: Use your smartphone as a calculator and receive a call? Especially in offices and business environments, investing in the Casio pocket/desktop calculator is worthwhile. This easy-to-use little helper ensures that fewer mistakes are made. The display of the model is large enough to show twelve digits. With the tiltable display, the numbers are always easy to read, which tends to lead to fewer errors. The calculator operates using a combination of solar and battery power. In favorable lighting conditions, the solar cells provide the necessary power. However, in darker conditions, the batteries take over. The calculator requires an LR54 type battery, which is already included.