一、口算。
3.14×0.2=
3.14×2×2=
12.56÷3.14÷2=
3.14×30=
3.14×0.1×2=
314÷3.14÷2=
7×3.14=
2×3.14×4=
785÷3.14÷2=
3.14×12=
2×3.14×0.5=
28.26÷3.14÷2=
3.14×0.5=
3.14×6×2=
62.8÷3.14÷2=
3.14×80=
3.14×2×100=
18.84÷3.14=
0.7×3.14=
3.14×8×2=
125.6÷3.14=
3.14×200=
2×3.14×9=
9.42÷3.14÷2=

$0.628$
$12.56$
$2$
$94.2$
$0.628$
$50$
$21.98$
$25.12$
$125$
$37.68$
$3.14$
$4.5$
$1.57$
$37.68$
$10$
$251.2$
$628$
$6$
$2.198$
$50.24$
$40$
$628$
$56.52$
$1.5$

二、计算下面各题，能用简便算法的就用简便算法。
$48×(\frac{5}{16}+\frac{5}{12}-\frac{7}{24})$
$\frac{18}{5}÷\frac{12}{5}×(\frac{1}{2}+\frac{2}{3})$
$11.9÷(0.9+0.8)×3.3$
$\frac{6}{7}×(7+9)×\frac{1}{18}$
$\frac{2}{3}×(\frac{3}{4}-\frac{1}{6})÷\frac{1}{5}$
$7.2÷[0.24×(18.8+31.2)]$

$21$
$\frac{7}{4}$
$23.1$
$\frac{16}{21}$
$\frac{35}{18}$
$0.6$