一、口算。
$0.8^2 =$
$0.96 - 0.7 =$
$3.14 × 1^2 =$
$20^2 =$
$0.99 ÷ 11 =$
$3.14 × 2^2 =$
$0.6^2 =$
$2.58 ÷ 0.3 =$
$3.14 × 3^2 =$
$50^2 =$
$0.65 + 2.35 =$
$3.14 × 0.1^2 =$
$11^2 =$
$0.12 × 0.5 =$
$3.14 × 0.2^2 =$
$0.9^2 =$
$3.6 ÷ 0.06 =$
$3.14 × 0.3^2 =$
$14^2 =$
$0.72 × 0.2 =$
$3.14 × 10^2 =$
$40^2 =$
$4.8 ÷ 12 =$
$3.14 × 20^2 =$
$0.3^2 =$
$0.45 × 20 =$
$3.14 × 30^2 =$
$60^2 =$
$875 ÷ 125 =$
$3.14 × 100^2 =$

0.8²=0.64
0.96-0.7=0.26
3.14×1²=3.14
20²=400
0.99÷11=0.09
3.14×2²=12.56
0.6²=0.36
2.58÷0.3=8.6
3.14×3²=28.26
50²=2500
0.65+2.35=3
3.14×0.1²=0.0314
11²=121
0.12×0.5=0.06
3.14×0.2²=0.1256
0.9²=0.81
3.6÷0.06=60
3.14×0.3²=0.2826
14²=196
0.72×0.2=0.144
3.14×10²=314
40²=1600
4.8÷12=0.4
3.14×20²=1256
0.3²=0.09
0.45×20=9
3.14×30²=2826
60²=3600
875÷125=7
3.14×100²=31400

二、计算下面各图形的面积。
1.
2.

1. $3.14×3^2=28.26(\mathrm{dm}^2)$
2. $3.14×(18÷2)^2=254.34(\mathrm{cm}^2)$