Ayin = 70, ordinal 16, reduced 7, no final form. Spelled in full, עין = 70+10+50 = 130.
Meaning
Ayin is both 'eye' and 'spring' or 'well' — one word for the organ of sight and the source of water, which the tradition treats as its happiest ambiguity. Its 70 is the number of the nations, of the elders who shared Moses' spirit, of the years of the exile, and of the 'seventy faces' of the Torah, so the letter's number is the number of the tradition's plurality.