Samekh = 60, ordinal 15, reduced 6, no final form. Spelled in full, סמך = 60+40+20 = 120.
Meaning
Samekh is 'prop' or 'support', one of the twelve simples, and its shape is a closed circle — the only letter that encloses itself, which the tradition reads as the cycle and as the support that holds what it encircles. Its 60 is the number of the sixty queens of the Song, and its name is the root of semikhah, the laying on of hands by which authority is transmitted.