1. 直接写出得数。
0.2×45=
0.62+0.4=
29.9+31.1=
(1.5+2.5)×0.11=
85÷$\frac{1}{2}$=
3.2×5=
78÷20=
2.8÷2.8+2.8=
2.4×0.4=
0.4×0.5=
13.7×0.2=
(1.2+0.7)×0.1=
3.07-1.32=
3.28+7.2=
7.3-5.25=
0.75×8×0.5=
24×0.5=
4.8÷0.5=
54×0.01=
2.8÷(2.8-1.4)=
$\frac{5}{9}×\frac{6}{7}$=
$\frac{3}{4}÷\frac{3}{5}$=
$\frac{3}{8}+\frac{1}{4}$=
$\frac{3}{4}÷\frac{1}{2}-\frac{3}{4}÷\frac{1}{2}$=

1. 0.2×45=9
0.62+0.4=1.02
29.9+31.1=61
(1.5+2.5)×0.11=0.44
85÷$\frac{1}{2}$=170
3.2×5=16
78÷20=3.9
2.8÷2.8+2.8=3.8
2.4×0.4=0.96
0.4×0.5=0.2
13.7×0.2=2.74
(1.2+0.7)×0.1=0.19
3.07-1.32=1.75
3.28+7.2=10.48
7.3-5.25=2.05
0.75×8×0.5=3
24×0.5=12
4.8÷0.5=9.6
54×0.01=0.54
2.8÷(2.8-1.4)=2
$\frac{5}{9}×\frac{6}{7}$=$\frac{10}{21}$
$\frac{3}{4}÷\frac{3}{5}$=$\frac{5}{4}$
$\frac{3}{8}+\frac{1}{4}$=$\frac{5}{8}$
$\frac{3}{4}÷\frac{1}{2}-\frac{3}{4}÷\frac{1}{2}$=0

2. 计算下面各题，怎样算简便就怎样算。
$\frac{1}{2}×3.2 +5.6×0.5 +1.2×0.5$
$(1 - \frac{6}{7}×\frac{5}{6})÷4$
$\frac{5}{14}÷7 + \frac{9}{14}×\frac{1}{7} + \frac{1}{2}$
$(16.25 - 3.47)÷1.25×0.8$
$4.8×7.8 +0.52×78$
$18÷[(1.5 -0.6)×0.4]$

2. $\frac{1}{2}×3.2 +5.6×0.5 +1.2×0.5$=5
$(1 - \frac{6}{7}×\frac{5}{6})÷4$=$\frac{1}{14}$
$\frac{5}{14}÷7 + \frac{9}{14}×\frac{1}{7} + \frac{1}{2}$=$\frac{9}{14}$
$(16.25 - 3.47)÷1.25×0.8$=8.1792
$4.8×7.8 +0.52×78$=78
$18÷[(1.5 -0.6)×0.4]$=50

照样子用简便方法计算。
$\frac{1}{3535} ÷ \frac{1}{5353}$
$= \frac{1}{3535} × 5353$
$= \frac{1}{35 × 101} × 101 × 53$
$= \frac{53}{35}$
$\frac{1}{6363} ÷ \frac{1}{3636}$
$\frac{1}{7272} ÷ \frac{1}{2727}$

$\frac{1}{6363} ÷ \frac{1}{3636}$
$= \frac{1}{6363} × 3636$
$= \frac{1}{63 × 101} × 101 × 36$
$= \frac{4}{7}$
$\frac{1}{7272} ÷ \frac{1}{2727}$
$= \frac{1}{7272} × 2727$
$= \frac{1}{72 × 101} × 101 × 27$
$= \frac{3}{8}$