《2025年文墨小学数学口算心算天天练五年级下册人教版》

① $\frac{13}{25} × \frac{10}{13} + \frac{4}{5} =$

答案： 先算乘法：$\frac{13}{25} × \frac{10}{13} = \frac{10}{25} = \frac{2}{5}$，再算加法：$\frac{2}{5} + \frac{4}{5} = \frac{6}{5}$

③ $\frac{3}{4} × 16 × \frac{5}{8} =$

答案： 从左到右计算：$\frac{3}{4} × 16 = 12$，$12 × \frac{5}{8} = \frac{60}{8} = \frac{15}{2}$

④ $\frac{5}{9} × 18 × \frac{3}{4} =$

答案： 从左到右计算：$\frac{5}{9} × 18 = 10$，$10 × \frac{3}{4} = \frac{30}{4} = \frac{15}{2}$

⑤ $13 × \frac{2}{13} × \frac{4}{15} =$

答案： 从左到右计算：$13 × \frac{2}{13} = 2$，$2 × \frac{4}{15} = \frac{8}{15}$

⑥ $\frac{8}{9} × \frac{3}{14} × \frac{7}{12} =$

答案： 从左到右计算：$\frac{8}{9} × \frac{3}{14} = \frac{24}{126} = \frac{4}{21}$，$\frac{4}{21} × \frac{7}{12} = \frac{28}{252} = \frac{1}{9}$

⑦ $\frac{1}{9} × 3 × 27 =$

答案： 从左到右计算：$\frac{1}{9} × 3 = \frac{1}{3}$，$\frac{1}{3} × 27 = 9$

⑧ $\frac{1}{10} × 50 × \frac{1}{20} =$

答案： 从左到右计算：$\frac{1}{10} × 50 = 5$，$5 × \frac{1}{20} = \frac{5}{20} = \frac{1}{4}$

⑨ $7 × \frac{1}{13} × 39 =$

答案： 从左到右计算：$7 × \frac{1}{13} = \frac{7}{13}$，$\frac{7}{13} × 39 = 21$

⑩ $76 × \frac{4}{19} × \frac{5}{16} =$

答案： 从左到右计算：$76 × \frac{4}{19} = 16$，$16 × \frac{5}{16} = 5$

⑪ $\frac{6}{17} × \frac{5}{18} × 17 =$

答案： 利用乘法交换律：$\frac{6}{17} × 17 × \frac{5}{18} = 6 × \frac{5}{18} = \frac{30}{18} = \frac{5}{3}$

⑮ $\frac{1}{40} × \frac{4}{5} × 80 =$

答案： 利用乘法交换律：$\frac{1}{40} × 80 × \frac{4}{5} = 2 × \frac{4}{5} = \frac{8}{5}$

⑰ $(33 + \frac{1}{5}) × \frac{5}{11} =$

答案： 利用乘法分配律：$33 × \frac{5}{11} + \frac{1}{5} × \frac{5}{11} = 15 + \frac{1}{11} = 15\frac{1}{11}$（或$\frac{166}{11}$）

⑱ $1 × \frac{1}{6} × \frac{12}{27} =$

答案： 从左到右计算：$1 × \frac{1}{6} = \frac{1}{6}$，$\frac{1}{6} × \frac{12}{27} = \frac{12}{162} = \frac{2}{27}$

⑳ $\frac{2}{3} × \frac{4}{13} + \frac{9}{13} × \frac{2}{3} =$

答案： 提取公因数$\frac{2}{3}$：$\frac{2}{3} × (\frac{4}{13} + \frac{9}{13}) = \frac{2}{3} × 1 = \frac{2}{3}$

㉑ $\frac{1}{6} × \frac{4}{9} × \frac{18}{23} =$

答案： 从左到右计算：$\frac{1}{6} × \frac{4}{9} = \frac{4}{54} = \frac{2}{27}$，$\frac{2}{27} × \frac{18}{23} = \frac{36}{621} = \frac{4}{69}$

㉒ $18 × \frac{2}{7} × \frac{7}{9} =$

答案： 利用乘法交换律：$18 × \frac{7}{9} × \frac{2}{7} = 14 × \frac{2}{7} = 4$