一、口算。
$0.2\div0.01=$ $0.25\times40=$ $2.7 - 0.53 + 0.47=$
$6 - 2.8=$ $0.83 + 0.38=$ $50\times(0.8 + 0.7)=$
$1.8\times90=$ $3.2\div0.8=$ $125\times0.08\times0.3=$
$0.91 - 0.76=$ $0.74 + 0.58=$ $8.01 + 0.89 + 1.99=$
$48\div0.12=$ $2.4\times5=$ $3 - 0.67 - 0.33=$
$0.081\times100=$ $0.72\div1.2=$ $1.45 + (3.5 - 1.45)=$
$10.8\div1.8=$ $0.43 - 0.3=$ $(6.9 - 2.4)\div3=$
$0.36\times0.4=$ $2.45\div0.7=$ $3.6\div0.9 - 4=$
$4.5 + 6.5=$ $0.19 - 0.1=$ $0.68 + 8\times0.5=$
$0.42\div0.6=$ $1.3\times0.6=$ $3.6 + 4 - 3.8=$

20 10 2.64
3.2 1.21 75
162 4 3
0.15 1.32 10.89
400 12 2
8.1 0.6 3.5
6 0.13 1.5
0.144 3.5 0
11 0.09 4.68
0.7 0.78 3.8

二、计算下面各题，怎样简便就怎样计算。
$2.8\times3.1 - 17.6\div8$ $6.33\times101 - 6.33$ $2.72\div[(8.2 - 6.5)\times0.5]$

6.48 633 3.2