$\frac{1}{6}$ и 0,2
$\frac{1}{6}=\frac{5}{30}$
$0,2=\frac{2}{10}=\frac{1}{5}=\frac{6}{30}$
$\frac{5}{30}<\frac{6}{30}$
$\frac{1}{6}<0,2$

$\frac{7}{9}$ и 0,77
$\frac{7}{9}=\frac{700}{900}$
$0,77=\frac{77}{100}=\frac{693}{900}$
$\frac{700}{900}>\frac{693}{900}$
$\frac{7}{9}>0,77$

−1,(645) и −1,(643)
−1,(645) = −1,645645...
−1,(643) = −1,643643...
−1,645645... < −1,643643...
−1,(645) < −1,(643)