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一、口算。
$490÷70=$
$2÷16=$
$2.18+3.72=$
$6.6×0.3=$
$480×20\% =$
$\frac {15}{16}÷\frac {4}{5}=$
$\frac {3}{8}÷\frac {9}{4}=$
$7.2÷0.36=$
$\frac {13}{16}-\frac {1}{4}=$
$\frac {2}{7}+\frac {3}{14}=$
$9.8-3.08=$
$\frac {7}{18}÷\frac {14}{15}=$
$\frac {11}{12}×18=$
$354+298=$
$\frac {5}{14}×\frac {7}{30}=$
$3.5×20\% =$
$1-\frac {3}{11}=$
$\frac {3}{8}+\frac {5}{9}=$
$\frac {3}{5}÷\frac {33}{20}=$
$12\% ×50=$
$\frac {20}{21}-\frac {4}{7}=$
$490÷70=$
7
$2÷16=$
0.125
$2.18+3.72=$
5.9
$6.6×0.3=$
1.98
$480×20\% =$
96
$\frac {15}{16}÷\frac {4}{5}=$
$\dfrac{75}{64}$
$\frac {3}{8}÷\frac {9}{4}=$
$\dfrac{1}{6}$
$7.2÷0.36=$
20
$\frac {13}{16}-\frac {1}{4}=$
$\dfrac{9}{16}$
$\frac {2}{7}+\frac {3}{14}=$
$\dfrac{1}{2}$
$9.8-3.08=$
6.72
$\frac {7}{18}÷\frac {14}{15}=$
$\dfrac{5}{12}$
$\frac {11}{12}×18=$
$\dfrac{33}{2}$
$354+298=$
652
$\frac {5}{14}×\frac {7}{30}=$
$\dfrac{1}{12}$
$3.5×20\% =$
0.7
$1-\frac {3}{11}=$
$\dfrac{8}{11}$
$\frac {3}{8}+\frac {5}{9}=$
$\dfrac{67}{72}$
$\frac {3}{5}÷\frac {33}{20}=$
$\dfrac{4}{11}$
$12\% ×50=$
6
$\frac {20}{21}-\frac {4}{7}=$
$\dfrac{8}{21}$
答案
一、7 0.125 5.9
1.98 96 $\dfrac{75}{64}$
$\dfrac{1}{6}$ 20 $\dfrac{9}{16}$
$\dfrac{1}{2}$ 6.72 $\dfrac{5}{12}$
$\dfrac{33}{2}$ 652 $\dfrac{1}{12}$
0.7 $\dfrac{8}{11}$ $\dfrac{67}{72}$
$\dfrac{4}{11}$ 6 $\dfrac{8}{21}$
1.98 96 $\dfrac{75}{64}$
$\dfrac{1}{6}$ 20 $\dfrac{9}{16}$
$\dfrac{1}{2}$ 6.72 $\dfrac{5}{12}$
$\dfrac{33}{2}$ 652 $\dfrac{1}{12}$
0.7 $\dfrac{8}{11}$ $\dfrac{67}{72}$
$\dfrac{4}{11}$ 6 $\dfrac{8}{21}$
二、计算下面各图形的表面积和体积。
答案
二、表面积：$\dfrac{1}{2}× 8× 6× 2+10× 6+10× 8+10× 10=288(\mathrm{cm}^2)$
体积：$6× 8× 10÷ 2=240(\mathrm{cm}^3)$
表面积：$(10× 8+10× 4+8× 4)× 2-3.14× (4÷ 2)^2× 2+3.14× 4× 4=329.12(\mathrm{cm}^2)$
体积：$10× 8× 4-3.14× (4÷ 2)^2× 4=269.76(\mathrm{cm}^3)$
体积：$6× 8× 10÷ 2=240(\mathrm{cm}^3)$
表面积：$(10× 8+10× 4+8× 4)× 2-3.14× (4÷ 2)^2× 2+3.14× 4× 4=329.12(\mathrm{cm}^2)$
体积：$10× 8× 4-3.14× (4÷ 2)^2× 4=269.76(\mathrm{cm}^3)$
