Giải bài 2 trang 90 - SGK Toán lớp 3
Tính:
a) \(\dfrac{\begin{align} & \,\,47 \\ & \times \\ & \,\,\,\,\,5 \\ \end{align}}{{}} \) \(\dfrac{\begin{align} & \,\,281 \\ & \times \\ & \,\,\,\,\,\,\,3 \\ \end{align}}{{}} \) \(\dfrac{\begin{align} & \,\,108 \\ & \times \\ & \,\,\,\,\,\,\,8 \\ \end{align}}{{}} \)
\(\dfrac{\begin{align} & \,\,75 \\ & \times \\ & \,\,\,\,\,6 \\ \end{align}}{{}} \) \(\dfrac{\begin{align} & \,\,419 \\ & \times \\ & \,\,\,\,\,\,\,2 \\ \end{align}}{{}} \)
b) \(\left. \begin{matrix} 872 \\ \,\,\,\,\,\, \\ \end{matrix} \right|\dfrac{2}{\,\,\,\,} \) \(\left. \begin{matrix} 261 \\ \,\,\,\,\,\, \\ \end{matrix} \right|\dfrac{3}{\,\,\,\,} \)
\(\left. \begin{matrix} 945 \\ \,\,\,\,\,\, \\ \end{matrix} \right|\dfrac{5}{\,\,\,\,} \) \(\left. \begin{matrix} 842 \\ \,\,\,\,\,\, \\ \end{matrix} \right|\dfrac{7}{\,\,\,\,} \)
Hướng dẫn:
Với phép nhân thực hiện nhân từ phải sang trái
Với phép chia ta chia từ trái qua phải
Bài giải:
a) \(\dfrac{\begin{align} & \,\,47 \\ & \times \\ & \,\,\,\,\,5 \\ \end{align}}{{235}} \) \(\dfrac{\begin{align} & \,\,281 \\ & \times \\ & \,\,\,\,\,\,\,3 \\ \end{align}}{{\,\,843}} \) \(\dfrac{\begin{align} & \,\,108 \\ & \times \\ & \,\,\,\,\,\,\,8 \\ \end{align}}{{\,\,864}} \)
\(\dfrac{\begin{align} & \,\,75 \\ & \times \\ & \,\,\,\,6 \\ \end{align}}{{450}} \) \(\dfrac{\begin{align} & \,\,419 \\ & \times \\ & \,\,\,\,\,\,2 \\ \end{align}}{{\,\,838}} \)
b) \(\left. \begin{align} & \begin{matrix} 872 \\ 07\,\, \\ \end{matrix} \\ & \,\,\,\,12\,\,\, \\ & \,\,\,\,\,\,\, 0 \\ \end{align} \right|\begin{matrix} \dfrac{2}{436} \\ {} \\ {} \\ \end{matrix} \) \(\left. \begin{align} & \begin{matrix} 261 \\ \,\,\,21 \\ \end{matrix} \\ & \,\,\,\,\,\,\,0 \end{align} \right|\begin{matrix} \dfrac{3}{87} \\ {} \\ \end{matrix} \)
\(\left. \begin{align} & \begin{matrix} 872 \\ 07\,\,\, \\ \end{matrix} \\ & \,\,\,\,12\,\,\, \\ & \,\,\,\,\,\,\, 0 \\ \end{align} \right|\begin{matrix} \dfrac{2}{436} \\ {} \\ {} \\ \end{matrix} \) \(\left. \begin{align} & \begin{matrix} 842 \\ 14\,\,\, \\ \end{matrix} \\ & \,\,\,\,02\,\,\, \\ & \,\,\,\,\,\,\, 2 \\ \end{align} \right|\begin{matrix} \dfrac{7}{120} \\ {} \\ {} \\ \end{matrix} \)
