1. 直接写出得数。
$9.56 + 0.4 =$
$5.4 ÷ 1.8 =$
$2.73 - 1.93 =$
$5 × (10 ÷ 0.1) =$
$0.18 × 4 =$
$0.9 × 0.2 =$
$0.91 × 7 =$
$3.48 ÷ 2.5 ÷ 0.4 =$
$1.08 ÷ 2 =$
$0.85 ÷ 0.5 =$
$2.4 ÷ 0.06 =$
$15 - 0.7 × 9 =$
$0.24 × 0.5 =$
$0.36 + 0.54 =$
$0.47 × 30 =$
$4.73 - 0.7 - 0.3 =$
$35 - 3.5 =$
$0.25 × 20 =$
$6.2 × 5 =$
$8.2 + 1.77 + 3.33 =$
$0.28 ÷ 0.14 =$
$0.81 + 0.9 =$
$0.63 + 0.7 =$
$4.2 ÷ 0.7 × 0.6 =$
$\frac{5}{27} ÷ \frac{1}{9} =$
$\frac{7}{36} ÷ \frac{21}{16} =$
$\frac{12}{5} × \frac{1}{24} =$
$\frac{1}{4} × 8.5 × 4 =$
$\frac{2}{3} + \frac{1}{6} =$
$\frac{8}{11} × \frac{3}{4} =$
$15 ÷ \frac{1}{5} =$
$\frac{4}{5} × 2 ÷ \frac{1}{5} =$

1. 9.96
3
0.8
500
0.72
0.18
6.37
3.48
0.54
1.7
40
8.7
0.12
0.9
14.1
3.73
31.5
5
31
13.3
2
1.71
1.33
3.6
$\frac{5}{3}$
$\frac{4}{27}$
$\frac{1}{10}$
8.5
$\frac{5}{6}$
$\frac{6}{11}$
75
8

2. 计算下面各题,怎样算简便就怎样算。
$\frac{14}{37} ÷ 7 + \frac{1}{7} × \frac{23}{37}$
$3.63 - (0.63 + 0.96 ÷ 3.2)$
$[ \frac{3}{5} - ( \frac{1}{5} - \frac{1}{3} ) ] ÷ \frac{4}{15}$
$3.54 ÷ 0.6 + 7.84$
$\frac{1}{12} ÷ ( \frac{3}{4} + \frac{1}{6} ) × 33$
$5.7 ÷ [ 0.76 ÷ (1.1 - 0.7) ]$

2. $\frac{1}{7}$
2.7
$\frac{11}{4}$
13.74
3
3

如图，线段AB是大圆的半径，线段OB是小圆的半径，AB = 15厘米，OB = 12厘米，则线段OA长多少厘米？

15+12-5=22(厘米)