《2025年文墨小学数学口算心算天天练五年级下册人教版》

① $35 × (\frac{1}{4} + \frac{1}{5}) =$

答案： 括号内通分：$\frac{1}{4} + \frac{1}{5} = \frac{5}{20} + \frac{4}{20} = \frac{9}{20}$，$35 × \frac{9}{20} = \frac{315}{20} = \frac{63}{4}$

② $64 × \frac{1}{8} × \frac{5}{8} =$

答案： 从左到右计算：$64 × \frac{1}{8} = 8$，$8 × \frac{5}{8} = 5$

③ $9 × \frac{2}{3} + \frac{1}{3} × 18 =$

答案： 分别计算乘法：$9 × \frac{2}{3} = 6$，$\frac{1}{3} × 18 = 6$，加法：$6 + 6 = 12$

④ $(\frac{1}{4} + \frac{1}{5}) × 20 =$

答案： 利用乘法分配律：$\frac{1}{4} × 20 + \frac{1}{5} × 20 = 5 + 4 = 9$

⑤ $(\frac{1}{2} + \frac{2}{5}) × 2 =$

答案： 利用乘法分配律：$\frac{1}{2} × 2 + \frac{2}{5} × 2 = 1 + \frac{4}{5} = \frac{9}{5}$

⑥ $\frac{1}{5} × 15 × \frac{1}{3} =$

答案： 从左到右计算：$\frac{1}{5} × 15 = 3$，$3 × \frac{1}{3} = 1$

⑦ $(\frac{4}{5} + \frac{1}{5}) × \frac{1}{18} =$

答案： 括号内相加：$\frac{4}{5} + \frac{1}{5} = 1$，$1 × \frac{1}{18} = \frac{1}{18}$

⑧ $\frac{1}{2} × \frac{1}{3} × \frac{2}{5} =$

答案： 从左到右计算：$\frac{1}{2} × \frac{1}{3} = \frac{1}{6}$，$\frac{1}{6} × \frac{2}{5} = \frac{2}{30} = \frac{1}{15}$

⑨ $7 × \frac{3}{7} × \frac{7}{9} =$

答案： 从左到右计算：$7 × \frac{3}{7} = 3$，$3 × \frac{7}{9} = \frac{21}{9} = \frac{7}{3}$

⑩ $\frac{1}{9} × 18 × \frac{1}{10} =$

答案： 从左到右计算：$\frac{1}{9} × 18 = 2$，$2 × \frac{1}{10} = \frac{1}{5}$

⑪ $19 × \frac{1}{8} × \frac{4}{19} =$

答案： 利用乘法交换律：$19 × \frac{4}{19} × \frac{1}{8} = 4 × \frac{1}{8} = \frac{1}{2}$

⑫ $8 × \frac{4}{5} × \frac{3}{10} =$

答案： 从左到右计算：$8 × \frac{4}{5} = \frac{32}{5}$，$\frac{32}{5} × \frac{3}{10} = \frac{96}{50} = \frac{48}{25}$

⑬ $28 × \frac{3}{8} × \frac{1}{7} =$

答案： 利用乘法交换律：$28 × \frac{1}{7} × \frac{3}{8} = 4 × \frac{3}{8} = \frac{12}{8} = \frac{3}{2}$

⑭ $(\frac{1}{4} × \frac{3}{4}) × \frac{10}{11} =$

答案： 先算括号内：$\frac{1}{4} × \frac{3}{4} = \frac{3}{16}$，$\frac{3}{16} × \frac{10}{11} = \frac{30}{176} = \frac{15}{88}$

⑮ $(\frac{1}{10} × \frac{5}{32}) × 64 =$

答案： 先算括号内：$\frac{1}{10} × \frac{5}{32} = \frac{5}{320} = \frac{1}{64}$，$\frac{1}{64} × 64 = 1$

⑯ $24 × (\frac{3}{8} + \frac{5}{6}) =$

答案： 利用乘法分配律：$24 × \frac{3}{8} + 24 × \frac{5}{6} = 9 + 20 = 29$

⑰ $\frac{1}{6} × 9 × \frac{5}{9} =$

答案： 利用乘法交换律：$\frac{1}{6} × (9 × \frac{5}{9}) = \frac{1}{6} × 5 = \frac{5}{6}$

⑱ $\frac{2}{9} × \frac{7}{20} × \frac{9}{11} =$

答案： 利用乘法交换律：$\frac{2}{9} × \frac{9}{11} × \frac{7}{20} = \frac{2}{11} × \frac{7}{20} = \frac{14}{220} = \frac{7}{110}$

⑲ $\frac{4}{5} × \frac{3}{8} × \frac{5}{9} =$

答案： 利用乘法交换律：$\frac{4}{5} × \frac{5}{9} × \frac{3}{8} = \frac{4}{9} × \frac{3}{8} = \frac{12}{72} = \frac{1}{6}$

⑳ $\frac{1}{3} × \frac{5}{8} × \frac{4}{5} =$

答案： 利用乘法交换律：$\frac{1}{3} × (\frac{5}{8} × \frac{4}{5}) = \frac{1}{3} × \frac{1}{2} = \frac{1}{6}$

㉑ $48 × (\frac{1}{12} + \frac{1}{10}) =$

答案： 利用乘法分配律：$48 × \frac{1}{12} + 48 × \frac{1}{10} = 4 + \frac{24}{5} = \frac{20}{5} + \frac{24}{5} = \frac{44}{5}$

㉒ $(\frac{7}{11} - \frac{3}{8}) × 88 =$

答案： 利用乘法分配律：$\frac{7}{11} × 88 - \frac{3}{8} × 88 = 56 - 33 = 23$