一、口算。
314÷3.14=
7÷1.4=
4.2×0.2=
0.6×3.14=
1.23+0.87=
24.06+0.4=
3.14×0.5=
3.5÷0.5=
4.2÷0.3=
3.14×0.9=
7.06−0.06=
0.6÷0.5=
3.14×0.7=
1.25×0.8=
2.07÷0.3=
3.14×0.3=
9.8+2.76=
0.99÷1.1=
157÷3.14=
9.1÷0.07=
6.4×0.5=
3.14×0.1=
4.9÷0.98=
7.1−1.05=
282.6÷3.14=
0.48÷0.3=
0.5×0.23=
0.628÷3.14=
0.4×500=
8.4÷60=

$100$
$5$
$0.84$
$1.884$
$2.1$
$24.46$
$1.57$
$7$
$14$
$2.826$
$7$
$1.2$
$2.198$
$1$
$6.9$
$0.942$
$12.56$
$0.9$
$50$
$130$
$3.2$
$0.314$
$5$
$6.05$
$90$
$1.6$
$0.115$
$0.2$
$200$
$0.14$

二、计算下面各图形的周长。
1.
2.

1. $3.14×10÷2+10=25.7(\mathrm{cm})$
2. $2×3.14×5÷4+5×2=17.85(\mathrm{dm})$