\[\boxed{\mathbf{4.}\mathbf{63}}\]
\[|42| = 42\]
\[|5,6| = 5,6\]
\[| - 3,1| = 3,1\]
\[\left| \frac{11}{15} \right| = \frac{11}{15}\]
\[\left| - \frac{4}{9} \right| = \frac{4}{9}\]
\[\left| - 7\ \frac{111}{400} \right| = 7\frac{111}{400}\]
\[| - 37| = 37\]
\[|0| = 0\]