Giải bài 1 trang 163 - SGK Toán lớp 4

a)       

  $\dfrac{\begin{align} & \,\,\,\,\,2057\\ & \times \\ & \,\,\,\,\,\,\,\,\,\,13\,\,\,\, \\ \end{align}}{\,\,\,\,6171}\\\underline{\,\,\,\,2057\,\,\,\,\,\,\,\,\,\,\,\,}\\\,\,\,\,26741$                         $\dfrac{\begin{align} & \,\,\,\,\,\,428\\ & \times \\ &\,\, \,\,\,\,\,125\,\,\,\, \\ \end{align}}{\,\,\,2140}\\\,\,\,\,\,\,856\,\\\underline{\,\,\,428\,\,\,\,\,\,\,\,\,\,\,\,}\\\,\,\,53500$                              

$\dfrac{\begin{align} & \,\,\,\,\,3167\\ & \times \\ &\,\,\,\,\,\,\,\,204\,\,\,\, \\ \end{align}}{\,12668}\\\underline{\,\,6334\,\,\,\,\,\,\,\,\,\,\,\,}\\\,\,646068$