The Pythagorean system lays the twenty six letters of the Latin alphabet across a grid of nine columns and repeats the sequence three times: A, J and S fall under 1; B, K and T under 2; C, L and U under 3, and so on through I, R and Z under 9. Every name and every date reduces to a single digit by adding its component numbers together and, if the result runs to two digits, adding those together again, a process called digit summing or theosophical reduction. A birth date of the fourth of July, 1990, for instance, sums each unit, 4 plus 7 plus 1 plus 9 plus 9 plus 0, and reduces the total the same way names are reduced.
Three totals are treated as exceptions and never reduced past two digits: 11, 22 and 33, called the master numbers. Practitioners read them as carrying an intensified version of the single digit they would otherwise reduce to, 2, 4 and 6 respectively, so a life path or name total landing on one of the three is read on its own terms rather than folded further. The grid itself is entirely mechanical once memorized; every calculation in the system, whether applied to a name, a birth date or an address, uses this same one to nine table and the same reduction rule, which is what makes the method easy to teach and to practise without specialist training.