Find the sum of the interior angles of a hendecagon (11-sided polygon).

The sum of the interior angles of a polygon can be calculated using the formula:

\[ \text{Sum of interior angles} = (n - 2) \times 180° \]

where \( n \) is the number of sides in the polygon.

For a hendecagon, \( n = 11 \):

\[ \text{Sum of interior angles} = (11 - 2) \times 180° = 9 \times 180° \]

Now, calculate \( 9 \times 180 \):

\[ 9 \times 180 = 1620° \]

Therefore, the sum of the interior angles of a hendecagon is \( \boxed{1620} \) degrees.