用简便方法计算2999ﾁ7ￊ7999ﾁ7ￊ799ﾁ7ￊ76

Question

如题所述

Answer 1

99ﾁ7ￊ799乘99ﾁ7ￊ899的简便运算 99ﾁ7ￊ799乘99ﾁ7ￊ899 =99+99*99+99 =99*（99+1）+99 =99*100+99 =9999。