しんぷる暗算 - ３０秒で脳トレしよっ is an engaging brain training game designed for iPhone users. This free application allows players to practice their mental arithmetic skills using all four basic operations: addition, subtraction, multiplication, and division. Users can select their preferred calculation method and adjust the difficulty level, making it suitable for both children and adults. The game encourages friendly competition, as players can challenge family members or friends to beat each other's scores.

The gameplay is simple yet effective; players have a limited time to solve as many problems as possible, with correct answers boosting their score and time. The app features a national ranking system, allowing users to compare their mental calculation skills with others worldwide. Additionally, players can review their answers after each game, enhancing their learning experience. This application is a fun way to improve mental math skills and engage in brain training.