そろボード is a free iPhone app developed by Digika Co.Ltd. that brings the traditional abacus to the digital world. With its patented touch technology, this app allows users to practice their math skills in a fun and interactive way.

In the "みえるモード" (Visible Mode), users can manipulate the beads on the virtual abacus by simply tapping on the screen. This mode is perfect for beginners, as it provides a visual representation of the calculations. The yellow beads are controlled with the thumb, the orange beads with the index finger, and the right hand is used for the ones place while the left hand is used for the tens place.

For a more challenging experience, users can switch to the "あんざんモード" (Mental Calculation Mode). In this mode, the beads are not shown on the screen, requiring users to mentally visualize the abacus and perform calculations. After completing the calculation, users can press the "珠表示" (Show Beads) button to reveal the answer.

Whether you're a beginner looking to improve your math skills or an advanced learner wanting to practice mental calculations, そろボード offers a unique and engaging way to learn math using the abacus. For those who want to dive deeper into abacus learning, the app also recommends the "そろタッチ" (Soro Touch) app, which requires separate membership registration.