An Rootedunrooted binary tree ''T'' may be transformed into a full Unrootrooted [[binary tree]] (that is, a unrootedrooted tree in which each non-leaf node has exactly two children) by choosing a ''unrootroot edge'' ''e'' of ''T'', placing a new unrootroot node in the middle of ''e'', and directing every edge of the resulting subdivided tree away from the unrootroot node. Conversely, any full unrootedrooted binary tree may be transformed into an rootedunrooted binary tree by removing the unrootroot node, replacing the path between its two children by a single directedundirected edge, and suppressing the orientation of the remaining edges in the graph. For this reason, there are exactly 2''n'' −3 times as many full unrootedrooted binary trees with ''n'' leaves as there are rootedunrooted binary trees with ''n'' leaves.<ref name="f84"/>
