《2025年亮点给力计算天天练五年级数学下册北师大版》

1. 直接写出得数。
$\frac{4}{5} \times \frac{5}{6} =$ $\frac{4}{5} \times \frac{5}{16} =$ $\frac{16}{9} \times \frac{3}{8} =$ $\frac{19}{50} \times \frac{10}{19} =$
$\frac{6}{13} \times \frac{1}{3} =$ $\frac{2}{25} \times \frac{10}{7} =$ $\frac{5}{16} \times \frac{4}{3} =$ $\frac{11}{28} \times \frac{8}{33} =$
$\frac{3}{4} \times \frac{7}{30} =$ $\frac{2}{7} + 2\frac{1}{3} =$ $\frac{2}{5} - \frac{1}{3} =$ $\frac{20}{39} \times \frac{13}{15} =$
$\frac{7}{24} \times \frac{16}{21} =$ $\frac{4}{7} \times \frac{5}{6} =$ $\frac{16}{9} \times \frac{3}{4} =$ $\frac{21}{25} \times \frac{5}{7} =$
$\frac{1}{3} - \frac{1}{8} =$ $\frac{35}{20} \times \frac{5}{14} =$ $\frac{11}{12} \times \frac{6}{11} =$ $\frac{3}{2} + \frac{2}{3} =$
$\frac{4}{15} \times 1\frac{7}{8} =$ $\frac{9}{5} \times \frac{20}{21} =$ $1\frac{1}{5} \times \frac{25}{3} =$ $\frac{8}{3} \times \frac{15}{24} =$

答案： $\frac{2}{3}$ $\frac{1}{4}$ $\frac{2}{3}$ $\frac{1}{5}$ $\frac{2}{13}$ $\frac{4}{35}$ $\frac{5}{12}$ $\frac{2}{21}$ $\frac{7}{40}$ $2\frac{13}{21}$ $\frac{1}{15}$ $\frac{4}{9}$ $\frac{2}{9}$ $\frac{10}{21}$ $\frac{4}{3}$ $\frac{3}{5}$ $\frac{5}{24}$ $\frac{5}{8}$ $\frac{1}{2}$ $\frac{13}{6}$ $\frac{1}{2}$ $\frac{12}{7}$ $10$ $\frac{5}{3}$

2. 计算下面各题。(写出计算过程)
$\frac{15}{29} \times \frac{58}{45}$ $\frac{11}{90} \times \frac{72}{55}$ $\frac{7}{120} \times \frac{24}{49}$

答案： $\frac{2}{3}$ $\frac{4}{25}$ $\frac{1}{35}$(计算过程略)

3. 在〇里填上“＞”“＜”或“=”。
$\frac{2}{3} \times \frac{3}{4} 〇 \frac{3}{4}$ $\frac{3}{8} \times 1 〇 \frac{3}{8}$ $\frac{3}{10} \times \frac{1}{9} 〇 \frac{5}{9} \times 0$
$\frac{5}{6} 〇 \frac{6}{5} \times \frac{5}{6}$ $1\frac{3}{7} \times \frac{8}{3} 〇 1\frac{3}{7}$ $\frac{7}{8} \times \frac{4}{3} 〇 \frac{7}{8} \times \frac{6}{5}$

答案： $＜$ $=$ $＞$ $＜$ $＞$ $＞$

·思维提升 定义新运算
规定：$a * b = \frac{a + b}{b - a} \times \frac{b}{a}(b ＞ a,a \neq 0)$。$3 * 8$的值是多少？

答案： $3*8=\frac{3 + 8}{8 - 3}\times\frac{8}{3}=\frac{11}{5}\times\frac{8}{3}=\frac{88}{15}$