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一、口算。
$5.7 + 0.33 =$
$\dfrac{7}{8} - \dfrac{5}{12} =$
$\dfrac{4}{5} + \dfrac{1}{2} =$
$8 ÷ 0.4 =$
$\dfrac{5}{8} - 50\% =$
$\dfrac{4}{5} × \dfrac{25}{48} =$
$\dfrac{13}{19} ÷ \dfrac{2}{19} =$
$5.7 + 0.33 =$
6.03
$0.49 - 0.21 =$0.28
$\dfrac{5}{8} + \dfrac{6}{7} =$$\frac{83}{56}$
$\dfrac{7}{8} - \dfrac{5}{12} =$
$\frac{11}{24}$
$30 × 0.01\% =$0.003
$90\% ÷ 60\% =$1.5
$\dfrac{4}{5} + \dfrac{1}{2} =$
$\frac{13}{10}$
$1 - 65\% =$35%
$20 × 45\% =$9
$8 ÷ 0.4 =$
20
$\dfrac{5}{3} - \dfrac{3}{5} =$$\frac{16}{15}$
$\dfrac{5}{6} + \dfrac{4}{15} =$$\frac{11}{10}$
$\dfrac{5}{8} - 50\% =$
$\frac{1}{8}$
$1.32 ÷ 1.2 =$1.1
$31.4 × 50 =$1570
$\dfrac{4}{5} × \dfrac{25}{48} =$
$\frac{5}{12}$
$99 ÷ 33\% =$300
$45\% - 22\% =$23%
$\dfrac{13}{19} ÷ \dfrac{2}{19} =$
$\frac{13}{2}$
$8\% × 400 =$32
$\dfrac{9}{20} ÷ \dfrac{3}{5} =$$\frac{3}{4}$
答案
一、6.03 0.28 $\frac{83}{56}$ $\frac{11}{24}$ 0.003 1.5 $\frac{13}{10}$ 35% 9 20 $\frac{16}{15}$ $\frac{11}{10}$ $\frac{1}{8}$ 1.1 1570 $\frac{5}{12}$ 300 23% $\frac{13}{2}$ 32 $\frac{3}{4}$
二、计算下面各题，怎样简便就怎样计算。
$\dfrac{5}{12} ÷ ( \dfrac{3}{2} - \dfrac{5}{7} - \dfrac{1}{7} )$ $72\% × \dfrac{5}{6} + 4 ÷ 1 \dfrac{3}{5}$ $7.1 × 42\% + 2.9 × 0.42$
$3.3 × 102$ $[ 574 - ( 63 + 77 ) ] ÷ 31$ $\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{3}{4} - \dfrac{2}{3} ) ]$
$\dfrac{5}{12} ÷ ( \dfrac{3}{2} - \dfrac{5}{7} - \dfrac{1}{7} )$ $72\% × \dfrac{5}{6} + 4 ÷ 1 \dfrac{3}{5}$ $7.1 × 42\% + 2.9 × 0.42$
$3.3 × 102$ $[ 574 - ( 63 + 77 ) ] ÷ 31$ $\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{3}{4} - \dfrac{2}{3} ) ]$
答案
二、$\frac{35}{54}$ $\frac{31}{10}$ 4.2 336.6 14 $\frac{4}{9}$
解析
$\dfrac{5}{12} ÷ ( \dfrac{3}{2} - \dfrac{5}{7} - \dfrac{1}{7} )$
$=\dfrac{5}{12} ÷ [ \dfrac{3}{2} - (\dfrac{5}{7} + \dfrac{1}{7}) ]$
$=\dfrac{5}{12} ÷ ( \dfrac{3}{2} - \dfrac{6}{7} )$
$=\dfrac{5}{12} ÷ ( \dfrac{21}{14} - \dfrac{12}{14} )$
$=\dfrac{5}{12} ÷ \dfrac{9}{14}$
$=\dfrac{5}{12} × \dfrac{14}{9}$
$=\dfrac{35}{54}$
$72\% × \dfrac{5}{6} + 4 ÷ 1 \dfrac{3}{5}$
$=0.72 × \dfrac{5}{6} + 4 ÷ \dfrac{8}{5}$
$=0.6 + 4 × \dfrac{5}{8}$
$=0.6 + 2.5$
$=\dfrac{3}{5} + \dfrac{5}{2}$
$=\dfrac{6}{10} + \dfrac{25}{10}$
$=\dfrac{31}{10}$
$7.1 × 42\% + 2.9 × 0.42$
$=7.1 × 0.42 + 2.9 × 0.42$
$=(7.1 + 2.9) × 0.42$
$=10 × 0.42$
$=4.2$
$3.3 × 102$
$=3.3 × (100 + 2)$
$=3.3 × 100 + 3.3 × 2$
$=330 + 6.6$
$=336.6$
$[ 574 - ( 63 + 77 ) ] ÷ 31$
$= [ 574 - 140 ] ÷ 31$
$=434 ÷ 31$
$=14$
$\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{3}{4} - \dfrac{2}{3} ) ]$
$=\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{9}{12} - \dfrac{8}{12} ) ]$
$=\dfrac{16}{27} ÷ ( \dfrac{1}{9} ÷ \dfrac{1}{12} )$
$=\dfrac{16}{27} ÷ ( \dfrac{1}{9} × 12 )$
$=\dfrac{16}{27} ÷ \dfrac{4}{3}$
$=\dfrac{16}{27} × \dfrac{3}{4}$
$=\dfrac{4}{9}$
$=\dfrac{5}{12} ÷ [ \dfrac{3}{2} - (\dfrac{5}{7} + \dfrac{1}{7}) ]$
$=\dfrac{5}{12} ÷ ( \dfrac{3}{2} - \dfrac{6}{7} )$
$=\dfrac{5}{12} ÷ ( \dfrac{21}{14} - \dfrac{12}{14} )$
$=\dfrac{5}{12} ÷ \dfrac{9}{14}$
$=\dfrac{5}{12} × \dfrac{14}{9}$
$=\dfrac{35}{54}$
$72\% × \dfrac{5}{6} + 4 ÷ 1 \dfrac{3}{5}$
$=0.72 × \dfrac{5}{6} + 4 ÷ \dfrac{8}{5}$
$=0.6 + 4 × \dfrac{5}{8}$
$=0.6 + 2.5$
$=\dfrac{3}{5} + \dfrac{5}{2}$
$=\dfrac{6}{10} + \dfrac{25}{10}$
$=\dfrac{31}{10}$
$7.1 × 42\% + 2.9 × 0.42$
$=7.1 × 0.42 + 2.9 × 0.42$
$=(7.1 + 2.9) × 0.42$
$=10 × 0.42$
$=4.2$
$3.3 × 102$
$=3.3 × (100 + 2)$
$=3.3 × 100 + 3.3 × 2$
$=330 + 6.6$
$=336.6$
$[ 574 - ( 63 + 77 ) ] ÷ 31$
$= [ 574 - 140 ] ÷ 31$
$=434 ÷ 31$
$=14$
$\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{3}{4} - \dfrac{2}{3} ) ]$
$=\dfrac{16}{27} ÷ [ \dfrac{1}{9} ÷ ( \dfrac{9}{12} - \dfrac{8}{12} ) ]$
$=\dfrac{16}{27} ÷ ( \dfrac{1}{9} ÷ \dfrac{1}{12} )$
$=\dfrac{16}{27} ÷ ( \dfrac{1}{9} × 12 )$
$=\dfrac{16}{27} ÷ \dfrac{4}{3}$
$=\dfrac{16}{27} × \dfrac{3}{4}$
$=\dfrac{4}{9}$
