在历届全国各地的初中数学竞赛试卷中，经常见到一些含有新规定的运算符号“。”的命题．由于这些新规定的运算与通常的四则运算不同，学生解答时往往感到比较困难．其实这类题目并不太难，只耍弄清楚新规定的运算与通常的四则运算之间的关系，把新规定的运算转化为通常的四则 In the examination papers of junior high school mathematics contests across the country, some of the propositions that contain the new operational symbol “.” Because these new rules are different from the usual four operations, students often find it difficult to answer. In fact, this type of problem is not too difficult. It is only necessary to make clear the relationship between the operation of the new rule and the usual four operations, and to translate the new operation into four general rules.