a) \(\overline {ab} .101 =\overline {ab} .(100+1)\)\(=\overline {ab}.100+\overline {ab} .1\)\(=\overline {ab00}+ab = \overline {abab} \)
b) \(\overline {abc} .7.11.13 = \overline {abc} .1001\)\(=\overline {abc}.(1000+1)\)\(=\overline {abc}.1000+\overline {abc}.1\)\(=\overline {abc000}+\overline {abc}\)\( = \overline {abcabc} \)
