1. 直接写出得数。
$ \frac{5}{12} + \frac{11}{12} = $$ $$ \frac{3}{9} + \frac{5}{9} = $$ $$ \frac{7}{8} - \frac{5}{8} = $$ $$ 2 - \frac{5}{7} - \frac{1}{7} = $
$ \frac{3}{14} + \frac{3}{14} = $$ $$ \frac{17}{27} + \frac{14}{27} = $$ $$ \frac{2}{3} + \frac{1}{3} = $$ $$ \frac{8}{15} + \frac{11}{15} - \frac{2}{15} = $
$ \frac{17}{13} - \frac{15}{13} = $$ $$ \frac{18}{33} - \frac{7}{33} = $$ $$ \frac{7}{18} - \frac{6}{18} = $$ $$ \frac{19}{17} - \frac{15}{17} + \frac{3}{17} = $
$ 5.6 ÷ 0.07 = $$ $$ 1.4 × 20 = $$ $$ 20 - 6.9 = $$ $$ 7.2 × 0.8 × 2.5 = $
$ 0.5 × 0.5 = $$ $$ 3.2 × 4 = $$ $$ 0.63 ÷ 9 = $$ $$ 7.5 - 4.22 - 1.28 = $
$ 0.88 + 1.2 = $$ $$ 26.7 - 0.75 = $$ $$ 3 - 1.36 = $$ $$ 48.5 ÷ 50 ÷ 2 = $
$ 4.8 ÷ 1.2 = $$ $$ 2.25 × 8 = $$ $$ 200 × 0.47 = $$ $$ 0.16 ÷ 0.4 × 1.5 = $

1. $\frac{16}{12}$ $\frac{8}{9}$ $\frac{2}{8}$ $\frac{8}{7}$
$\frac{6}{14}$ $\frac{31}{27}$ 1 $\frac{17}{15}$
$\frac{2}{13}$ $\frac{11}{33}$ $\frac{1}{18}$ $\frac{7}{17}$
80 28 13.1 14.4
0.25 12.8 0.07 2
2.08 25.95 1.64 0.485
4 18 94 0.6

2. 解方程。
$ x + 2 - 2.6 = 3.22 $$ $$ x ÷ 5 - 3.08 = 4.46 $$ $$ 2 × (1.5x + 6) = 12.6 $
$ 7x + 5.6 = 41.3 $$ $$ 4x + 3.5x = 22.5 $$ $$ 9 × 6.5 + 0.4x = 87.5 $

2. $x = 3.82$ $x = 37.7$ $x = 0.2$
$x = 5.1$ $x = 3$ $x = 72.5$

把 \frac{5}{13} 化成小数后，小数部分的前100位数字之和是多少？

$\frac{5}{13}=0.384615384615···$
$100÷6=16$(组)$······4$(个)
$3 + 8 + 4 + 6 + 1 + 5 = 27$
$27×16 = 432$
$432 + 3 + 8 + 4 + 6 = 453$