\[\boxed{\mathbf{705}.}\]
\[1)\ 12 = 2^{2} \cdot 3;\ \ 18 = 2 \cdot 3^{2}\]
\[НОД(12;18) = 2 \cdot 3 = 6.\]
\[2)\ 24 = 2^{3} \cdot 3;\ \ \ 30 = 2 \cdot 3 \cdot 5\]
\[НОД(24;30) = 2 \cdot 3 = 6.\]
\[3)\ 6 = 2 \cdot 3;\ \ \ 36 = 2^{2} \cdot 3^{2}\]
\[НОД(6;36) = 2 \cdot 3 = 6.\]
\[4)\ 48 = 2^{4} \cdot 3;\ \ \ 64 = 2^{6}\]
\[НОД(48;64) = 2^{4} = 16.\]
\[5)\ 35 = 5 \cdot 7;\ \ \ 18 = 2 \cdot 3²\]
\[НОД(35;18) = 1.\]
\[6)\ 14 = 2 \cdot 7;\ \ 21 = 3 \cdot 7;\ \ \]
\[28 = 2^{2} \cdot 7\]
\[НОД(14;21;28) = 7.\]