\[\boxed{\text{4.\ 344}}\]
\[\textbf{а)}\ \frac{4}{9} = 0,(4)\]
\[\textbf{б)}\frac{8}{15} = 0,5(3)\]
\[\textbf{в)}\ \frac{29}{80} = 0,3625\]
\[\textbf{г)}\ \frac{11}{18} = 0,6(1)\]
\[\textbf{д)}\ 6\frac{9}{20} = 6\frac{45}{100} = 6,45\]
\[\textbf{е)}\ 3\frac{7}{12} = 3,58(3)\]
\[\textbf{ж)}\ 4\frac{7}{24} = 4,291(6)\]
\[\textbf{з)}\ 2\frac{21}{56} = 2\frac{3}{8} = 2,375\]