一、口算。
6.8 + 8.4 =
3.6÷0.09 =
6.6×0.3 =
24÷0.6 =
0.1×0.01 =
100 - 0.02 =
3.5×0.2 =
5.9 - 5 =
12÷30 =
4.2 - 0.21 =
7.8÷0.6 =
3.07×1000 =
0.8 + 0.18 =
2.2×4 =
2.09 + 9.1 =
0.36×300 =
0.68 + 0.42 =
8.4÷0.6 =
3.4 - 1.4 =
0.18×0.3 =
0.89 - 0.25 =
0.34÷17 =
7.82 - 7.2 =
0.74×5 =
1.03×5 =
30÷0.3 =
2.6 + 1.47 =
0.45 + 5.5 =
1.25×0.8 =
0.52÷0.4 =

15.2 40 1.98
40 0.001 99.98
0.7 0.9 0.4
3.99 13 3070
0.98 8.8 11.19
108 1.1 14
2 0.054 0.64
0.02 0.62 3.7
5.15 100 4.07
5.95 1 1.3

二、计算下面各题，怎样简便就怎样计算。
47.6 - 7.6÷0.25
2.64×9.9 + 0.264
30.4 - 27.5÷(2.75÷0.25)

17.2 26.4 27.9