1. 直接写出得数。(16☆)
21.3×0.1=
4.5×0.3=
0.3×2.1=
0.2×1.1=
0.5×0.6=
2.1×0.6=
0.8×1.2=
0.91×0.1=
0.5×2.5=
0.5×4.9=
0.3×0.8=
0.6×3.1=
2.7×0.4=
3.6×0.5=
0.8×3.2=
8.1×0.9=
7.8×0.4=
2.1×0.7=
4.8×0.2=
3.2×0.4=
1.12×0.5=
0.096×10=
0.5×3.5=
1.12×0.2=
5.2×0.4=
7.1×0.6=
0.6×2.4=
17.1×0.1=
144.2×0.01=
4.2×0.8=
24.5×0.2=
2.34×0.2=

1. 21.3×0.1=2.13
4.5×0.3=1.35
0.3×2.1=0.63
0.2×1.1=0.22
0.5×0.6=0.3
2.1×0.6=1.26
0.8×1.2=0.96
0.91×0.1=0.091
0.5×2.5=1.25
0.5×4.9=2.45
0.3×0.8=0.24
0.6×3.1=1.86
2.7×0.4=1.08
3.6×0.5=1.8
0.8×3.2=2.56
8.1×0.9=7.29
7.8×0.4=3.12
2.1×0.7=1.47
4.8×0.2=0.96
3.2×0.4=1.28
1.12×0.5=0.56
0.096×10=0.96
0.5×3.5=1.75
1.12×0.2=0.224
5.2×0.4=2.08
7.1×0.6=4.26
0.6×2.4=1.44
17.1×0.1=1.71
144.2×0.01=1.442
4.2×0.8=3.36
24.5×0.2=4.9
2.34×0.2=0.468

2. 根据$278×25=6950$，直接写出下面各题的积。(16☆)
$2.78×25=$
$27.8×25=$
$2.78×2.5=$
$27.8×2.5=$
$27.8×0.25=$
$0.278×250=$
$0.278×25=$
$278×0.025=$

2. $2.78×25=69.5$
$27.8×25=695$
$2.78×2.5=6.95$
$27.8×2.5=69.5$
$27.8×0.25=6.95$
$0.278×250=69.5$
$0.278×25=6.95$
$278×0.025=6.95$

3. 用竖式计算。(18☆)
5.7×1.2
3.19×1.8
29.4×0.65
1.08×7.5
3.88×4.3
2.25×1.6

3. 5.7×1.2=6.84
3.19×1.8=5.742
29.4×0.65=19.11
1.08×7.5=8.1
3.88×4.3=16.684
2.25×1.6=3.6