\[\boxed{\mathbf{1.}}\]
\[На\ 5\ делятся\ произведения:\]
\[13 \cdot 15\]
\[48 \cdot 20\]
\[25 \cdot 100\]
\[\boxed{\mathbf{2.}}\]
\[1)\ 21 = 7 \cdot 3\]
\[2)\ 84 = 7 \cdot 12\]
\[3)\ 70 = 7 \cdot 10\]
\[4)\ 105 = 7 \cdot 15\]
\[\boxed{\mathbf{3.}}\]
\[1)\ 39 + 120 = 3 \cdot (13 + 40)\]
\[2)\ 60 + 27 = 3 \cdot (20 + 9)\]
\[\boxed{\mathbf{4.}}\]
\[Не\ делятся\ на\ 10:\]
\[25 + 110\]
\[28 + 50\]
\[160 + 37\]
\[\mathbf{16.\ 1.\ Признаки\ делимости\ на\ 10,\ 5,\ 2,\ и\ 4}\]
\[\boxed{\mathbf{1.}}\]
\[1)\ на\ 2:\]
\[18,\ 20,\ 22,\ 24,\ 26,\ 28,\ 30,\ \]
\[32,\ 34,\ 36,\ 38\]
\[2)\ на\ 5:\]
\[20,\ 25,\ 30,\ 35.\]
\[3)\ на\ 10:\ \ \]
\[20,\ 30.\]
\[4)\ на\ 4:\ \ \]
\[20,\ 24,\ 28,\ 32,\ 36.\]