1. 直接写出得数。
实际用时：分钟
$10×120=$ $280÷20=$ $\frac{7}{40}÷\frac{7}{8}=$ $\frac{39}{50}×\frac{10}{13}=$
$0.5×2.6=$ $3.14×40=$ $\frac{4}{5}-\frac{3}{4}=$ $\frac{3}{20}+\frac{2}{5}=$
$17+83=$ $0.96÷8=$ $45×\frac{8}{15}=$ $\frac{3}{5}-\frac{1}{10}=$
$1.06×5=$ $2.8÷0.2=$ $\frac{35}{19}÷7=$ $\frac{3}{10}+\frac{1}{3}=$
$245-114=$ $50×11=$ $\frac{3}{4}-\frac{2}{9}=$ $\frac{13}{32}×\frac{4}{13}=$
$3.14×6=$ $2.5×100=$ $\frac{1}{2}×\frac{2}{5}=$ $1÷\frac{20}{33}=$
$240×10=$ $0.32÷0.4=$ $\frac{1}{2}×\frac{7}{8}=$ $\frac{1}{3}+\frac{2}{7}=$
$350-205=$ $68÷34=$ $\frac{1}{3}×\frac{8}{9}=$ $\frac{3}{5}÷\frac{2}{7}=$
$3.14×8=$ $150×20=$ $\frac{7}{8}-\frac{3}{4}=$ $\frac{15}{16}÷\frac{5}{4}=$
$260÷20=$ $16÷0.5=$ $21×\frac{5}{7}=$ $\frac{2}{5}+\frac{3}{8}=$

1. 1200 14 $\frac{1}{5}$ $\frac{3}{5}$
1.3 125.6 $\frac{1}{20}$ $\frac{11}{20}$
100 0.12 24 $\frac{1}{2}$
5.3 14 $\frac{5}{19}$ $\frac{19}{30}$
131 550 $\frac{19}{36}$ $\frac{1}{8}$
18.84 250 $\frac{1}{5}$ $\frac{33}{20}$
2400 0.8 $\frac{7}{16}$ $\frac{13}{21}$
145 2 $\frac{8}{27}$ $\frac{21}{10}$
25.12 3000 $\frac{1}{8}$ $\frac{3}{4}$
13 32 15 $\frac{31}{40}$

2. 计算下面各题。
$50÷1.25÷0.8$
$9.87×101-9.87$
$350÷[7×(115-65)]$
$\frac{5}{7}+\frac{1}{6}-\frac{2}{7}$
$\frac{1}{4}-\frac{1}{6}+\frac{2}{3}$
$\frac{3}{5}+\frac{3}{2}-\frac{1}{4}$

2. 50 987 1
$\frac{25}{42}$ $\frac{3}{4}$ $\frac{37}{20}$