用简便方法计算．0.3×2.5×0.4 0.78×101 2.5×（8+0.4） 1.25×0.7×0.8 9.8×2.5 50.8×101-50.8 4.6×99+4.6 0.25×32×0.125 38.2×8+61.8×8．
| ①0.3×2.5×0.4 =0.3×（2.5×0.4） =0.3×1 =0.3； ②0.78×101 =0.78×（100+1） =0.78×100+0.78 =78+0.78 =78.78； ③2.5×（8+0.4） =2.5×8+2.5×0.4 =20+1 =21； ④1.25×0.7×0.8 =（1.25×0.8）×0.7 =1×0.7 =0.7； ⑤9.8×2.5 =（10-0.2）×2.5 =10×2.5-0.2×2.5 =25-0.5 =24.5； ⑥50.8×101-50.8 =50.8×（101-1） =50.8×100 =5080； ⑦4.6×99+4.6 =4.6×（99+1） =4.6×100 =460； ⑧0.25×32×0.125 =0.25×4×8×0.125 =（0.25×4）×（8×0.125） =1×1 =1； ⑨38.2×8+61.8×8 =（38.2+61.8）×8 =100×8 =800． |
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