1. 直接写出得数。
7.5 - 2.8 =
5.5 - 3.2 =
1 - 0.2 =
4 - 3.5×0.1 =
5.3÷0.53 =
0.23×400 =
0.59 + 0.22 =
2.75 + 6.8 - 1.9 =
6 - 0.08 =
2.1÷0.7 =
2÷5 =
1.48÷0.2 - 2.5 =
3.7×3 =
0.02 + 6.78 =
3.5×60 =
(4.25 + 2.75)÷0.2 =
75÷$\frac{25}{14}$ =
6.5×$\frac{1}{5}$ =
$\frac{10}{9}$÷$\frac{2}{9}$ =
50 - 50×$\frac{1}{5}$ =
12×$\frac{5}{8}$ =
$\frac{3}{8}$÷$\frac{1}{6}$ =
$\frac{7}{30}$÷$\frac{3}{20}$ =
$\frac{2}{3}$ + $\frac{1}{3}$×$\frac{2}{5}$ =
0.6×$\frac{10}{21}$ =
$\frac{3}{22}$÷$\frac{6}{11}$ =
$\frac{5}{6}$×$\frac{42}{55}$ =
1.8×$\frac{9}{16}$ - $\frac{9}{16}$ =
10÷$\frac{4}{15}$ =
16÷$\frac{8}{21}$ =
$\frac{4}{9}$×$\frac{21}{20}$ =
10 - 2÷$\frac{1}{4}$ =

1. 4.7
2.3
0.8
3.65
10
92
0.81
7.65
5.92
3
0.4
4.9
11.1
6.8
210
35
42
1.3
5
40
$\frac{15}{2}$
$\frac{9}{4}$
$\frac{14}{9}$
$\frac{4}{5}$
$\frac{2}{7}$
$\frac{1}{4}$
$\frac{7}{11}$
$\frac{9}{20}$
$\frac{75}{2}$
42
$\frac{7}{15}$
2

2. 计算下面各题，怎样算简便就怎样算。
$2.6×1.02$
$(9.5 - 3.8)÷2.5÷4$
$3.14 - (2.14 + 4×\frac{11}{50})$
$\frac{7}{10}×\frac{4}{9} + \frac{5}{9}×\frac{7}{10}$
$0.8÷[(\frac{5}{9} - \frac{1}{2})÷\frac{5}{9}]$
$(\frac{2}{5} + \frac{3}{8})÷(\frac{9}{10} - \frac{3}{4})$

2. 2.652
0.57
$\frac{3}{25}$
$\frac{7}{10}$
8
$\frac{31}{6}$

巧算:11×12.12−12×11.11。

原式 = 11 × 12 × 1. 01 − 12 × 11×1.01
=0