Yinyang is one word or one line, Yin Yang are two words or two lines formed when the word Yinyang is divided into two words or when the single line Yinyang is broken into two lines: Yin Ying.
Yin is 'Yin Yang' because Yin is dominant whenever the two words are separate. Yang is Yinyang because Yang is dominanant whenever the two words are united .
Yin and Yang are darkness and light respectively. And darkness can only persist in the absence of light. Uniting Yin and Yang to form Yinyang is like bringing light to darkness.
Yin and Yang are earth and sky respectively. Yin rules when heaven (the sky) and the earth are separate, Yang rules when heaven and earth are united.
God lives in heaven (the sky) and man lives on earth. God rules when the earth and the sky are united, and man rules when the earth and the sky are separate. This means that man is Yin and God is Yang.
The relationship between Yin and Yang is explained by binary black hole merger. One of the blacks is Yin and the other is Yang. The two black holes are 'Yin Yang' or Yin when they are separated, and Yinyang or Yang when they are united.
The Holy of Holies is Yang (Yinyang) because the two squares or the two circles (the two glories) are aligned.
Yin is equal to 2 (even number) because it is made up of the two separate words Yin Yang, Yang is equal to 1 (odd number) because it is equal to the one world Yinyang.