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．