First, find the sum of the interior angles using the formula: (𝒏 – 2) × 180 = (8 – 2) × 180 = 6 × 180 = 1080. Then divide this by the number of sides, eight: 1080 divided by 8 = 135.

The formula for calculating the sum of interior angles is \((n - 2) \times 180^\circ\) where \(n\) is the number of sides. All the interior angles in a regular polygon are equal.