Inverse element : Each symmetry has an inverse: ⁠ i d ⁠, the reflections ⁠ f h ⁠, ⁠ f v ⁠, ⁠ f d ⁠, ⁠ f c ⁠ and the 180° rotation r 2 are their own inverse, because performing them twice brings the square back to its original orientation. The rotations r 3 and r 1 are each other's inverses, because rotating 90° and then rotation 270° (or vice versa) yields a rotation over 360° which leaves the square unchanged. This is easily verified on the table.