\[\boxed{\text{88.}}\]
\[7\ ч\ вечера = 19\ ч.\]
\[19\ ч - 6\ ч = 13\ (ч) -\]
\[продолжался\ день.\]
\[Ответ:13\ ч.\]
\[\boxed{\text{89.}}\]
\[18 = 1\ дес\ .\ 8\ ед.\]
\[27 = 2\ дес.\ 7\ ед.\]
\[39 = 3\ дес.\ 9\ ед.\]
\[48 = 4\ дес.\ 8\ ед.\]
\[287 = 2\ сот.\ 8\ дес.\ 7\ ед.\]
\[340 = 3\ сот.\ 4\ дес.\ 0\ ед.\]
\[805 = 8\ сот.\ 0\ дес.\ 5\ ед.\]
\[975 = 9\ сот.\ 7\ дес.\ 5\ ед.\]
\[\boxed{\text{90.}}\]
\[Однозначные\ числа:\ \ \]
\[2,\ 3,\ 7,\ 9,\ 1.\]
\[Двузначные\ числа:\ \ \]
\[21,\ 38,\ 71,\ 45,\ 66.\]
\[Трехзначные\ числа:\]
\[189,\ 271,\ 562,\ 684,\ \]
\[999.\]
\[\boxed{\text{91.}}\]
\[385 = 300 + 80 + 5\]
\[380 = 300 + 80\]
\[305 = 300 + 5\]
\[426 = 400 + 20 + 6\]
\[760 = 700 + 60\]
\[249 = 200 + 40 + 9\]
\[777 = 700 + 70 + 7\]
\[752 = 700 + 50 + 2\]
\[\boxed{\text{92.}}\]
\[1)\ 3 \cdot 8\ :4 = 24\ :4 = 6\]
\[2)\ 27\ :3 \cdot 5 = 9 \cdot 5 = 45\]
\[3)\ (48 + 15)\ :9 = 63\ :9 = 7\]
\[4)\ (81 + 9)\ :10 = 90\ :10 = 9\]
\[5)\ (73 - 28)\ :5 = 45\ :5 = 9\]
\[6)\ (64 - 56) \cdot 7 = 8 \cdot 7 = 56\]
\[7)\ (37 + 23)\ :6 = 60\ :6 = 10\]