登录
一、口算。
$3.8 - 0.38 = $
$5.25÷0.5 = $
$0.65×0.2 = $
$2.22 + 1.88 = $
$2 - 1.08 = $
$2.5×8 = $
$\frac{2}{7} + \frac{1}{6} = $
$\frac{1}{2} - \frac{2}{5} = $
$3.8 - 0.38 = $
3.42
$8.1÷2.7 = $3
$0.6÷0.3 + 0.5 = $2.5
$5.25÷0.5 = $
10.5
$1.9×4 = $7.6
$1.8÷0.9×0.5 = $1
$0.65×0.2 = $
0.13
$9.8 - 0.98 = $8.82
$(1 - 0.1)×0.1 = $0.09
$2.22 + 1.88 = $
4.1
$1.3×0.7 = $0.91
$0.9×7 + 10.7 = $17
$2 - 1.08 = $
0.92
$8.8÷0.4 = $22
$(1.6 + 2.4)÷5 = $0.8
$2.5×8 = $
20
$2.74 - 1.73 = $1.01
$2.5×0.9×4 = $9
$\frac{2}{7} + \frac{1}{6} = $
$\frac{19}{42}$
$\frac{1}{6} - \frac{1}{12} = $$\frac{1}{12}$
$\frac{4}{5} + \frac{2}{7} + \frac{1}{5} = $$\frac{9}{7}$
$\frac{1}{2} - \frac{2}{5} = $
$\frac{1}{10}$
$\frac{7}{15} + \frac{1}{20} = $$\frac{31}{60}$
$\frac{3}{2} - (\frac{7}{8} - \frac{1}{2}) = $$\frac{9}{8}$
答案
3.42 3 2.5 10.5 7.6 1 0.13 8.82 0.09 4.1 0.91 17 0.92 22 0.8 20 1.01 9 $\frac{19}{42}$ $\frac{1}{12}$ $\frac{9}{7}$ $\frac{1}{10}$ $\frac{31}{60}$ $\frac{9}{8}$
二、计算长方体和正方体的表面积。
答案
$(6×5+6×3.5+5×3.5)×2=137(cm^{2})$ $6×6×6=216(cm^{2})$
解析
长方体表面积：$(6×5+6×3.5+5×3.5)×2=137(cm^{2})$
正方体表面积：$6×6×6=216(cm^{2})$
正方体表面积：$6×6×6=216(cm^{2})$
