1. $\frac{7}{13} × 4 × \frac{26}{35}$ $5 × 8 × (\frac{3}{5} × \frac{7}{8})$
$1.85 × 4 × 0.25$ $1.25 × 2.5 × 32$
答案：$\frac{7}{13}×4×\frac{26}{35}$
$=(\frac{7}{13}×\frac{26}{35})×4$
$=\frac{2}{5}×4$
$=\frac{8}{5}$
$5×8×(\frac{3}{5}×\frac{7}{8})$
$=(5×\frac{3}{5})×(8×\frac{7}{8})$
$=3×7$
$=21$
$1.85×4×0.25$
$=1.85×(4×0.25)$
$=1.85×1$
$=1.85$
$1.25×2.5×32$
$=1.25×2.5×(8×4)$
$=(1.25×8)×(2.5×4)$
$=10×10$
$=100$
2. $24×(\frac{3}{8}+\frac{3}{4}-\frac{5}{6})$ $5.6×9.9+5.6×0.1$
$\frac{4}{5}×\frac{2}{9}+\frac{4}{5}÷\frac{9}{7}-\frac{4}{5}$ $6.3×9.8$
$\frac{6}{17}×\frac{8}{21}+\frac{8}{17}×\frac{11}{21}$ $\frac{5}{9}×\frac{10}{21}+\frac{5}{9}×\frac{2}{21}+\frac{4}{7}×\frac{4}{9}$
$41.7×4.3+43×0.71+512×0.43$
$6066\frac{6066}{6067}×\frac{1}{6068}$
答案：$24×(\frac{3}{8}+\frac{3}{4}-\frac{5}{6})$
$=24×\frac{3}{8}+24×\frac{3}{4}-24×\frac{5}{6}$
$=9+18-20$
$=7$
$5.6×9.9+5.6×0.1$
$=5.6×(9.9+0.1)$
$=5.6×10$
$=56$
$\frac{4}{5}×\frac{2}{9}+\frac{4}{5}÷\frac{9}{7}-\frac{4}{5}$
$=\frac{4}{5}×\frac{2}{9}+\frac{4}{5}×\frac{7}{9}-\frac{4}{5}×1$
$=\frac{4}{5}×(\frac{2}{9}+\frac{7}{9}-1)$
$=\frac{4}{5}×0$
$=0$
$6.3×9.8$
$=6.3×(10-0.2)$
$=6.3×10-6.3×0.2$
$=63-1.26$
$=61.74$
$\frac{6}{17}×\frac{8}{21}+\frac{8}{17}×\frac{11}{21}$
$=\frac{8}{17}×\frac{6}{21}+\frac{8}{17}×\frac{11}{21}$
$=\frac{8}{17}×(\frac{6}{21}+\frac{11}{21})$
$=\frac{8}{17}×\frac{17}{21}$
$=\frac{8}{21}$
$\frac{5}{9}×\frac{10}{21}+\frac{5}{9}×\frac{2}{21}+\frac{4}{7}×\frac{4}{9}$
$=\frac{5}{9}×(\frac{10}{21}+\frac{2}{21})+\frac{16}{63}$
$=\frac{5}{9}×\frac{4}{7}+\frac{16}{63}$
$=\frac{20}{63}+\frac{16}{63}$
$=\frac{36}{63}$
$=\frac{4}{7}$
$41.7×4.3+43×0.71+512×0.43$
$=41.7×4.3+4.3×7.1+4.3×51.2$
$=4.3×(41.7+7.1+51.2)$
$=4.3×100$
$=430$
$6066\frac{6066}{6067}×\frac{1}{6068}$
$=(6066×\frac{6067+1}{6067})×\frac{1}{6068}$
$=6066×\frac{6068}{6067}×\frac{1}{6068}$
$=\frac{6066}{6067}$
3. $19.23 ÷ 0.25 ÷ 0.4$
$\frac{7}{13} ÷ ( \frac{7}{13} × \frac{8}{13} )$
答案：$19.23 ÷ 0.25 ÷ 0.4$
$=19.23 ÷ (0.25 × 0.4)$
$=19.23 ÷ 0.1$
$=192.3$
$\frac{7}{13} ÷ ( \frac{7}{13} × \frac{8}{13} )$
$=\frac{7}{13} ÷ \frac{7}{13} ÷ \frac{8}{13}$
$=1 ÷ \frac{8}{13}$
$=\frac{13}{8}$
4. $49.36 - 10.56 - 0.44$
$\frac{5}{8} ÷ [ \frac{13}{12} - ( \frac{1}{12} + \frac{1}{4} ) ]$
答案：$49.36 - 10.56 - 0.44$
$= 49.36 - (10.56 + 0.44)$
$= 49.36 - 11$
$= 38.36$
$\frac{5}{8} ÷ [ \frac{13}{12} - ( \frac{1}{12} + \frac{1}{4} ) ]$
$= \frac{5}{8} ÷ [ \frac{13}{12} - \frac{1}{12} - \frac{1}{4} ]$
$= \frac{5}{8} ÷ [ 1 - \frac{1}{4} ]$
$= \frac{5}{8} ÷ \frac{3}{4}$
$= \frac{5}{8} × \frac{4}{3}$
$= \frac{5}{6}$
5. $\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}$
答案：$\begin{aligned}&\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\\=&1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}-\frac{1}{64}+\frac{1}{64}-\frac{1}{128}\\=&1-\frac{1}{128}\\=&\frac{127}{128}\end{aligned}$
