long multiplication

例句：

1. 1.The teacher explained the long multiplication problemto the students.
   老师向学生们解释了长乘法问题。
2. 2. Long multiplication is a complexoperation that requires careful calculation.
   长乘法是一种复杂的运算，需要仔细计算。
3. 3. In mathematics, long multiplication is usedto calculate large numbers quickly.
   在数学中，长乘法用于快速计算大数。