\[Страница\ 28.\]
\[\boxed{\mathbf{4}.}\]
\[\textbf{а)}\]
\[\textbf{б)}\]
\[\textbf{в)}\]
\[\textbf{г)}\]
\[\textbf{д)}\ \]
\[\boxed{\mathbf{5}.}\]
\[\textbf{а)}\ 17 + 5 \cdot 0 = 17 + 0 = 17\]
\[\textbf{б)}\ 24 \cdot 1 + 39 = 24 + 39 = 63\]
\[\textbf{в)}\ 8 \cdot 0 + 46 \cdot 1 + 58 =\]
\[= 0 + 46 + 58 = 104\]
\[\boxed{\mathbf{6}.}\]
\[\textbf{а)}\ 561 \cdot 5 \cdot 2 = 561 \cdot (5 \cdot 2) =\]
\[= 561 \cdot 10 = 5610\]
\[\textbf{б)}\ 25 \cdot 349 \cdot 4 = (25 \cdot 4) \cdot 349 =\]
\[= 100 \cdot 349 = 34\ 900\]
\[\textbf{в)}\ 8 \cdot 416 \cdot 125 =\]
\[= (8 \cdot 125) \cdot 416 =\]
\[= 1000 \cdot 416 = 416\ 000\]