\[\boxed{\text{123}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[586 \cdot 10 \cdot 7 = 586 \cdot 70,\ так\ как\ \]
\[586 \cdot 70 = 586 \cdot (7 \cdot 10) =\]
\[= 586 \cdot 7 \cdot 10.\]
\[36 \cdot 800 = 36 \cdot 8 \cdot 100,\ так\ как\ \]
\[36 \cdot 800 = 36 \cdot (8 \cdot 100) =\]
\[= 36 \cdot 8 \cdot 100.\]
\[1\ 200\ :20 > 1\ 200\ :100\ :2,\ \]
\[так\ как\ 1\ 200\ :100\ :2 =\]
\[= 1\ 200\ :200.\]
\[900\ :10\ :5 = 900\ :50,\ так\ как\ \]
\[900\ :10\ :5 = 900\ :50.\ \]