一、口算。
0.68÷4=
3.64×20=
(13.5−12.5)÷2=
7.7÷77=
0.46×0.2=
9.5÷0.5÷2=
18.9+0.21=
14÷20=
6.66+2×0.8=
7.56−3.12=
2.75+32.5=
3.95+2.4×0.5=
714÷7=
0.9−0.09=
8×21×1.25=
$\frac{9}{32}÷\frac{3}{4}=$
$\frac{3}{4}×\frac{16}{15}=$
$(\frac{9}{10}−\frac{2}{5})÷4=$
$\frac{1}{2}+\frac{1}{5}=$
$\frac{2}{9}÷\frac{1}{2}=$
$\frac{2}{3}×0.25÷\frac{3}{50}=$
$0.6×\frac{10}{11}=$
$\frac{7}{8}×\frac{12}{13}=$
$24×(\frac{3}{5}÷\frac{1}{5})=$

0.68÷4=0.17
3.64×20=72.8
(13.5−12.5)÷2=0.5
7.7÷77=0.1
0.46×0.2=0.092
9.5÷0.5÷2=9.5
18.9+0.21=19.11
14÷20=0.7
6.66+2×0.8=8.26
7.56−3.12=4.44
2.75+32.5=35.25
3.95+2.4×0.5=5.15
714÷7=102
0.9−0.09=0.81
8×21×1.25=210
$\frac{9}{32}÷\frac{3}{4}=\frac{3}{8}$
$\frac{3}{4}×\frac{16}{15}=\frac{4}{5}$
$(\frac{9}{10}−\frac{2}{5})÷4=\frac{1}{8}$
$\frac{1}{2}+\frac{1}{5}=\frac{7}{10}$
$\frac{2}{9}÷\frac{1}{2}=\frac{4}{9}$
$\frac{2}{3}×0.25÷\frac{3}{50}=\frac{25}{9}$
$0.6×\frac{10}{11}=\frac{6}{11}$
$\frac{7}{8}×\frac{12}{13}=\frac{21}{26}$
$24×(\frac{3}{5}÷\frac{1}{5})=72$

二、计算下面各图形中涂色部分的面积。
1.
2.

1. $(3+3)×(3+3)-3.14×3^2=7.74(\mathrm{cm}^2)$
2. $3.14×(4÷2)^2×2=25.12(\mathrm{dm}^2)$