### What is the sum of all interior angles of a polygon of $10$ sides$?$

$16 \text{ right angles }$
1. We know that the sum of all interior angles of a polygon of $n$ sides is $(2n - 4)$ right angles.
2. \begin{align} \text{ Sum of all interior angles of the polygon of } 10 \text{ sides } &= ( 2 \times 10 - 4 ) \text{ right angles } \\ &= 16 \text{ right angles } \end{align}