下面各题怎样简便就怎样计算 9.9×25 0.75×0.5×4×0.2 1.25×32×0.25 8.12×4+1.88×4 0.32×13.4-0.32×3.4 3.84×99+3.84 2.009×390+20.09×41+200.9×
问题描述：
| 下面各题怎样简便就怎样计算 9.9×25 |
0.75×0.5×4×0.2 |
| 1.25×32×0.25 | 8.12×4+1.88×4 |
| 0.32×13.4-0.32×3.4 | 3.84×99+3.84 |
| 2.009×390+20.09×41+200.9×2 | （9.57+9.57+9.57+9.57 ）×25． |
答
（1）9.9×25，=（10-0.1）×25，=10×25-0.1×25，=250-2.5，=247.5；（2）0.75×0.5×4×0.2，=（0.75×4）×（0.5×0.2），=3×0.1，=0.3；（3）1.25×32×0.25，=1.25×8×4×0.25，=（1.25×8）×（0.25×4），...