1.直接写得数。
0.2×0.4=
8.2×2=
50×7.5=
2.5×0.4=
3.2×3=
3.5×20=
3.99×1=
0×3.52=
1.5×5=

0.08
16.4
375
1
9.6
70
3.99
0
7.5

2.列竖式计算。
42×5.4=
5.6×1.8=
0.25×0.046=

42×5.4=226.8
竖式：
42
×5.4
----
168
210
----
226.8
5.6×1.8=10.08
竖式：
5.6
×1.8
----
448
56
----
10.08
0.25×0.046=0.0115
竖式：
0.25
×0.046
------
150
100
------
0.0115

3.怎么简便就怎么算。
0.125×32
0.78×101
3.26×5.7－3.26×0.7
56.5×99＋56.5
1.25×213×0.8
156×1.7－56×1.7

0.125×32
=0.125×8×4
=1×4
=4
0.78×101
=0.78×(100+1)
=0.78×100 + 0.78×1
=78 + 0.78
=78.78
3.26×5.7－3.26×0.7
=3.26×(5.7－0.7)
=3.26×5
=16.3
56.5×99＋56.5
=56.5×(99+1)
=56.5×100
=5650
1.25×213×0.8
=1.25×0.8×213
=1×213
=213
156×1.7－56×1.7
=1.7×(156－56)
=1.7×100
=170