《2025年口算训练六年级数学下册北师大版升级版》

初出茅庐
$\frac{5}{9} \times \frac{7}{10} \div \frac{7}{9} =$
$1 \div \frac{5}{8} \times \frac{5}{8} =$
$\frac{4}{7} \div \frac{16}{21} \times \frac{1}{3} =$
$\frac{1}{9} \div (\frac{1}{2} - \frac{1}{3}) =$
$\frac{6}{7} \div \frac{3}{14} \div \frac{2}{3} =$
$1.5 \times 8 \times \frac{1}{6} =$
$\frac{3}{5} \times \frac{2}{5} \times \frac{5}{12} =$
$\frac{1}{7} \times 42 \times \frac{1}{6} =$
$\frac{3}{8} \times 72 + 8 =$
$\frac{4}{5} \div \frac{2}{3} \div \frac{3}{5} =$
$(0.875 + \frac{1}{8}) \times \frac{1}{8} =$
$(0.375 + \frac{5}{8}) \times \frac{1}{16} =$
$24 \times (\frac{3}{8} + \frac{5}{6}) =$
$\frac{7}{9} \div \frac{11}{5} + \frac{5}{11} \times \frac{2}{9} =$
$17 \div 51 + (\frac{1}{68} + \frac{2}{51}) \times 17 =$

答案：

过关斩将
$200 \times (1 + 20\%) =$
$420 \times 60\% \times 50\% =$
$312 \div (1 + 4\%) =$
$20000 \times 2.94\% \times 2 =$
$2.4 \times (1 - 10\%) =$
$4000 \times 3.85\% \times 5 =$
$15.5 \div (1 - 95\%) =$
$650 \div (1 + 30\%) =$
$5000 \times 2.94\% \times 2 =$
$2.4 \times (1 + 10\%) =$
$30000 \times 3.85\% \times 3 =$
$9.6 \div (1 - 60\%) =$
$500 \times (1 - 40\%) =$
$420 \div 60\% \times 50\% =$
$1200 \times (1 - 10\%) =$
$10000 \times 3.85\% \times 3 =$
$9.6 \div (1 + 60\%) =$
$90000 \times 3.85\% \times 5 =$

答案：

一种树苗的成活率为70%~80%，至少应栽多少棵才能确保成活200棵？
秘籍点拨 要“确保成活200棵树苗”，应该选择最低的成活率计算。

答案：