If I recall correctly (which may or may not be the case), a few years ago I encountered – very briefly in the writing of Anthony Louis and then more exhaustively in that of James Wanless – the notion of decimal counterparts among the trump cards of the tarot. The assumption is that the two-digit trumps (Wheel of Fortune through World) with a final digit in the “tens” position that is identical to that of the single-digit trumps (Fool through Hermit) share a sympathetic bond with the earlier trumps in both spirit and substance (mathematically, it looks like this: 1 ~ x1; 2 ~ x2; 3 ~ x3, etc.) At the time I was thoroughly steeped in the concept of theosophical reduction (adding two digits together to produce a single-digit number: 19 = 1+9 = 10; 1+0 = 1 and so forth), so these ideas didn’t have much of an impact on me.
Lately, however, in reading Alejandro Jodorowsky’s Way of Tarot (which otherwise didn’t impress me), I came upon a more rational approach that I think I can work with in practical ways. First a housekeeping note: the numerical notation must be “normalized” according to Arabic rather than Roman conventions in order for this to work smoothly. Trying to stay with the archaic Roman numerals of the Tarot de Marseille (e.g. Temperance as “XIIII;” Sun as “XVIIII”) can create a hopeless muddle in which too many cards can potentially be linked to the Magician (there is a more logical way to do this). Modern Roman numerals are better for this purpose but not much: is the trump numbered fourteen, Temperance, associated with the Emperor (4 ~ x4) or the Hierophant when expressed as XIV? The more economical Arabic numbers eliminate any potential confusion (even though theosophical reduction tells us that “14” is related to “5,” not “4”).
I also steered well clear of Jodo’s more fanciful connections between the trumps based on visual correlations that are often tenuous at best and silly at worst. I can’t quite get behind the assumption that, since both Strength and the World happen to have a Lion on them, they are somehow markedly similar in nature; too many metaphysical lines are blurred for this to be a convincing technique, especially when divining with the cards. By sticking with Arabic numbers, I arrive at the following relatively “clean” pairs and triplets. I find it intriguing (but probably not significant) that theosophical reduction of the two-digit number yields the trump card (or two) after that of the associated single-digit trump.
The Fool (0), the Wheel of Fortune (10) and Judgement (20) – three instances of “starting over”
The Magician (1), Justice (11) and the World (21)
The High Priestess (2) and the Hanged Man (12)
The Empress (3) and Death (13)
The Emperor (4) and Temperance (14)
The Hierophant (5) and the Devil (15)
The Lovers (6) and the Tower (16)
The Chariot (7) and the Star (17)
Strength (8) and the Moon (18)
The Hermit (9) and the Sun (19)
I plan to treat these combinations as secondary to the parallels drawn by using theosophical reduction. Meanwhile, as a learning exercise, I’ll continue to contemplate the subtleties produced by their interaction. Regarding the Magician, for every two-digit trump that begins with “1,” the assumption in parade parlance is that the Magician would function as the “grand marshal” or procession leader who lends direction and “force of will” to the actions described by the digit following it. The mathematical expression would be “1x,” and while we’re at it, for the High Priestess it would be “2x” (the Priestess in both Judgement and the World).