this is an abacus app . An abacus is a calculating tool that has been used since ancient times. It consists of rows of movable beads, strung on a wire. They represent digits. One of the two numbers is set up, and the beads are manipulated to perform an operation such as addition, or even a square or cubic root. you can choose the style from various beautiful styles. Image by brgfx on Freepik : https://rb.gy/penfgq