Exercise 6.1

There are two possible options for \(b\) such that \(\overline{3} \cdot b = 0\). They are \(\overline{4}\) and \(\overline{8}\); notice that

\[\overline{3} \cdot \overline{4} = \overline{3 \times 4} = \overline{12} = \overline{0}\]

and also that

\[\overline{3} \cdot \overline{8} = \overline{3 \times 8} = \overline{24} = \overline{0}.\]