no. of no. of orientable type of Results of cut: half boundaries non-orientable cut no. of loops? length and twists of the width? no. of twists? no. surface of knots? orientable? 0 center 0 one-third 1 center 1 one-third 2 center 2 one-third 3 center 3 one-third 4 center 4 one-third