Giải bài 1 trang 88 - SGK Toán lớp 4

a)   

\(\left. \begin{align} & \begin{matrix} 62321\\ \,\,\,\,\,00921\,\,\,\,\, \\ \end{matrix} \\ & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0\\\ \end{align} \right|\begin{matrix} \dfrac{\,\,\,\,307\,\,\,\,\,\,\,}{a203\,\,} {} \\ {} \\\\\end{matrix}\)