\[\boxed{\mathbf{Проверочная\ работа\ №3.\ Повторение}}\]
\[\boxed{\text{1.}}\]
\[7 - 2,3 = 4,7.\ \ \ \]
\[\boxed{\text{2.}}\]
\[4 - \frac{2}{7} = 3\frac{7}{7} - \frac{2}{7} = 3\frac{5}{7}\text{.\ \ \ }\]
\[\boxed{\text{3.}}\]
\[0,27 + 0,73 = 1.\ \ \ \]
\[\boxed{\text{4.}}\]
\[\frac{1}{4} + 0,3 = 0,25 + 0,3 = 0,55.\ \ \ \]
\[\boxed{\text{5.}}\]
\[{0,01}^{3} = 0,01 \cdot 0,01 \cdot 0,01 =\]
\[= 0,000001.\ \ \ \]
\[\boxed{\text{6.}}\]
\[21\ \%\ от\ 300\ \Longrightarrow\]
\[\Longrightarrow 300\ :100 \cdot 21 = 3 \cdot 21 = 63.\text{\ \ }\]
\[Ответ:63.\ \ \]
\[\boxed{\text{7.}}\]
\[Нет.\ \ \]
\[(3,3 + 1,5)\ :2 = 4,8\ :2 = 2,4.\ \ \ \]
\[\boxed{\text{8.}}\]
\[Да.\]