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.

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．