The length of the diagonal of a cube can be calculated by the formula
[tex]\begin{gathered} d=a\sqrt[]{3} \\ \text{where a is one side of the cube} \\ a=60 \end{gathered}[/tex]Hence,
[tex]\begin{gathered} d=60\sqrt[]{3}\text{ units} \\ d=103.92\text{ units (2 decimal place)} \end{gathered}[/tex]