manual calculating unit

例句：

1. 1. This manual calculating unit is very useful for beginners.
   这个手动计算单元对于初学者来说非常实用。
2. 2.The engineer used a manual calculating unit to calculate the dimensions of the building.
   工程师使用手动计算器来计算建筑物的尺寸。
3. 3. The manual calculating unit was used to perform calculations on the data collected by the surveyor.
   手动计算器被用来对调查员收集的数据进行计算。