Each file of 9 sub-abacus is a tool to solve mathematical problems. It consists of nine grids, and each grid can be filled with a number. With given constraints, students can fill these grids by reasoning and inference, so as to find out the solution to the problem.

Each file of 9 sub-abacus can be used to solve a variety of mathematical problems, such as linear equations, equations, inequalities, expression evaluation and so on. It can cultivate students' logical thinking ability, reasoning ability and problem-solving ability.

Each file of 9 abacus can help students better understand mathematical concepts and enhance their interest and love for mathematics.