Not difficult. The first chapter "Decimal" in the second volume of seventh grade mathematics of Zhejiang Education Press is relatively easy. This chapter mainly explains the definition, counting and four operations of decimals, focusing on the addition, subtraction, multiplication and division of decimals and the conversion between decimals and fractions. Decimal is one of the very basic concepts in mathematics, and it is the basis of subsequent mathematics learning. It is suggested to study and master it carefully.