\[\boxed{\mathbf{Страница\ 16.}еуроки - ответы\ на\ пятёрку}\]
\[\boxed{\mathbf{52.}}\]
\[2 \cdot 30 = 60\]
\[4 \cdot 200 = 800\]
\[90 \cdot 5 = 450\]
\[100 \cdot 6 = 600\]
\[\boxed{\mathbf{53.}}\]
\[6\ м = 600\ см\]
\[2\ м\ 8\ дм = 280\ см\]
\[2\ м\ 80\ см = 280\ см\]
\[10\ м\ 5\ дм\ 4\ см = 1054\ см\]
\[\boxed{\mathbf{54.}}\]
\[Способ\ 1.\]
\[40\ мм \cdot 2 + 60\ мм \cdot 2 = 200\ мм.\]
\[Способ\ 2.\]
\[(40 + 60) \cdot 2 = 200\ мм.\]
\[Ответ:20\ см.\]
\[\boxed{\mathbf{55.}}\]
\[Верные\ равенства:\]
\[x + a = a + x\]
\[c - 0 = c + 0\]
\[\boxed{\mathbf{56.}}\]
\[15 + 8 = 23\]
\[25 + 9 = 34\]
\[36 + 4 = 40\]
\[54 + 5 = 59\]
\[27 + 6 = 33\]
\[45 + 8 = 53\]
\[\boxed{\mathbf{57.}}\]
\[28\ :7 = 4 \cdot 6 = 24\]
\[72\ :8 = 9\ :9 = 1\]
\[6 + 564 = 570 - 4 = 566\]
\[1)\ 566 + 4 = 570\]
\[2)\ 570 - 564 = 6\ \]
\[64\ :8 = 8 + 992 = 1000\]
\[1)\ 1000 - 992 = 8\]
\[2)\ 8 \cdot 8 = 64\]