Indian tradition is unusually rich in eighteens, most of them clustered around the Mahabharata. The epic has eighteen books, its central war lasts eighteen days, and the armies that fight it number eighteen akshauhinis; the Bhagavad Gita, set on that battlefield, has exactly eighteen chapters, and its teaching is sometimes read as turning on the number. Beyond the epic, the Puranas are traditionally counted as eighteen major texts with eighteen minor ones. East Asian Buddhism expanded the sixteen arhats to a set of eighteen, the Luohan of Chinese temples. The eighteen of India is thus a number of totality within a tradition, quite independent of the Hebrew chai, and the coincidence of two major cultures loading the same number with meaning for unrelated reasons is a good caution against reading significance across traditions.
Balliett's 1908 chart and its later elaborators reduce eighteen to nine, completion and humanitarian breadth in the standard modern keyword list, a root the American system shares with twenty-seven and thirty-six; none of Balliett, Cheiro, Florence Campbell or Juno Jordan drew on the Hebrew chai or the Mahabharata's eighteens already described in building that reading, so the American nine-root and the two older eighteens described above are three independent bodies of association converging, by coincidence of arithmetic rather than of source, on the same number.