Matemáticas 9 años by The City of the Apps is a free Android game that helps children in fourth grade to review their math curriculum in an enjoyable way. The game offers more than 1000 questions divided into 15 topics, including addition, subtraction, multiplication, division, fractions, decimals, measurements, angles, plane figures, and statistics.

The game is specially designed for 9-year-old children and features a map of topics that must be completed to reach the final exam. The game is easy to play and can be enjoyed without an internet connection.

Overall, Matemáticas 9 años is a great educational game for children who want to reinforce their knowledge of math in a fun and interactive way.