The Birthday Number

The Birthday number is the simplest of the numerological figures: it is just the day of the month on which a person was born, reduced to a single digit (or kept as a master number). Because it is taken from the day alone rather than the whole date or the name, it is treated as a secondary and more specific indicator than the Life Path, a particular gift or talent the person brings, a note within the larger theme of the life. Its very simplicity makes it the one figure in the system that requires no chart and no reduction of a name. It forms part of the standard set of core numbers in the Pythagorean numerology assembled in the United States in the early twentieth century by L. Dow Balliett and codified by Juno Jordan and others; like the rest of that system it is modern, conventionally called Pythagorean but not descended from any ancient practice attributed to Pythagoras.

Cheiro's 1926 Book of Numbers and Florence Campbell's 1931 Your Days Are Numbered both elaborated the wider chart this simplest of figures sits within, though the Birthday number itself changed little across their editions precisely because, as this article already notes, it requires no letter chart and no name at all. Walter Burkert's study of the Pythagorean tradition finds no descent from Pythagoras for any part of this apparatus, and the scholarly verdict on the system's claimed pedigree is that it has been largely abandoned as a comparative category.