tính 13 + 18
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\(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{13}\\{18}\end{array}} \\\,\,\,\,31\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{35}\\{46}\end{array}} \\\,\,\,\,81\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{36}\\{36}\end{array}} \\\,\,\,\,72\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{17}\\{16}\end{array}} \\\,\,\,\,33\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{28}\\{34}\end{array}} \\\,\,\,\,62\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{18}\\{57}\end{array}} \\\,\,\,\,75\end{array}\) | \(\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{19}\\{21}\end{array}} \\\,\,\,\,40\end{array}\) | \[\begin{array}{l}\underline { + \begin{array}{*{20}{c}}{69}\\{12}\end{array}} \\\,\,\,\,81\end{array}\] |