As LRichard says: there is no correlation between the numbering of the trumps and the letters as numbers. For one, any such breaks down after number 10, and two, there are only 21 numbered trumps and there are 22 letter/numbers. I personally doubt there was any original intention to correlate the two, and consider the appropriation of tarot into esoteric schemes to most likely be a later development.*
For my own purposes I first consider, without reference to the Hebrew letters, where does the fool make sense to me when considered as part of an allegorical sequence - and the most sense to me is at the beginning (albeit in general terms, as the old Italian proberb has it, he is 'here, there and everywhere'). Then I attribute them on a one to one sequential basis (using the TdM pattern, not the GD/Waite variation thereof#) and consider in what respect is this or that card may be likened to this or that letter. For example, in respect of Fool (un-number or zero) and Alef/One, there is the old myth of the letters God approaches to be first in creation and working backwards stops at Beth, in respect of which Alef is thus an exception in terms of the rest (21 letters approached and Alef not) just as the Fool is an exception (21 numbered trumps and the Fool). Kabbalistically, Beth (2) is symbolic of 'the beginning' not Alef (1) and thus appears appropriate in that respect to an attribution with Trump 1 as the beginning of the trump sequence. Each of the letters are said to draw upon a related Sefiroth, for example Alef to Keter (called 'Ain' - nothing in the Zohar) and Beth to Chokmah (called 'beginning' and 'primal point' in the Zohar), Gimel to Binah etc.
Moses Cordovero** explains in his 'Garden of Pomegranates' that Alef is the letter from which the rest are drawn^, and that the rest are split into three groups of seven - the first seven, commencing with Beth, are grouped under the rule of grace, the second seven are grouped into the rule of love, and the third under the rule of Judgment. Thus again, like we have the Fool and 21 trumps, we have Alef and then the other 21 letters (grouped into three groups of seven, as esotericists and occultists commonly do with the 21 trumps^^).
Kwaw
* Which may be taken to mean, as has been mentioned, that any arbitrary attribution may considered 'right'. But that is true enough any way, in as much as each of the letters are connected to each and every sefiroth. A relationship that is apparent if we model the paths in accordance with the Sefer Yetzirah, as ten concentric circles with 22 paths radiating from the center.
# I prefer the 'Fortune trumped by Fortitude' of the TdM pattern as more in keeping with renaissance humanist pairing of Fortune/Virtu (fortezza) as found for example in the works of Petrarch, Albierti. Mirandola, Bruno, etc., :
"Humanists often figured “the heroic ability to master Fortune” in Hercules... In Bruno’s ‘Explusion’, Fortune fails to usurp Hercules’ celestial place. He displays ‘fortezza’, “ the strength of the human will..., the ‘domitrice della fortuna... a heroic passion”, analogous to Machiavelli’s ‘virtu’ (“ability, power, forcefulness, industry, valor”), “often counterposed to the word Fortune”.
end quote from “English Revenge Drama” by Woodbridge, p.113.
** There are many schools of Kabbalah in Judaism, but for classification purposes can be described basically under two, Lurianic and non-Lurianic. Moses Cordovero was an exponent of pre-Lurianic kabbalah - and it is his work that mainly informed Christian and Hermetic Kabbalah (for example, the Tree of Life we are most familiar with from the Western Esoteric Schools is one of two described in Cordovero's 'Garden of Pomegranates - the GD also had another Tree in its cipher manuscripts but as far as I know no material in relation it has ever been published and probably was never written). Modern Judaic Kabbalah is mainly post-Gra Lurianic, thus one of the aspects in which the traditions have diverged (although there are some modern decks that have been made based upon Gra/Lurianic kabbalah and correspondences). Unlike the Western Esoteric Schools however, each of which likes to insist its own version is right and the others wrong - in Judaic Kabbalah each may be considered right at different times, or to different people or in different places according to individual understanding. Thus, up to the 20th century at least, the Zohar (in Mishnaic like fashion) would be published with commentaries by both Lurianic and non-Lurianic commentators, with no declamations of one being right or the other wrong (even though they may offer widely different and often opposing interpretations).
^ Just as the rest of the letters draw upon Alef, so we might say also that the Game of Tarot itself draws upon the special aspect of the Fool (indeed, so much so the very name of the Game - Tarocchi - most likely means 'Fool').
^^ And as I am inclined to do myself too. For as we find below the World with its symbols Ezekiel's chariot in the top row the Chariot in the bottom row, note too in similar fashion - below Judgement, which in Augustinian theology is an aspect of God's caritas (love), lies cupiditas (love, represented by Eros - together with an emblem of the two types of love); below the Sun is one of the two medieval 'lights of world' the Pope (attributed to the Sun); below the Moon the other of the two 'lights of the World' the Emperor (whose attribution as one of the two lights of the World is to the Moon); beneath the Star, symbol of the Virgin Mary Queen of Heaven, Empress of Hell, is the Empress; below the House of God is the Popesse, emblem of the RC Church; and below the trickster and deceiver the Devil is the trickster and deceiver the Bateleur.