Two calculators can both show their working and still disagree, because traditions branch at a handful of well-defined points. This page isolates those points and runs the same input through both readings, so you can see which one your source uses instead of guessing why the numbers moved.
1. The order of the sums
The largest visible difference comes from how a birth date is added. The 1926 handbook adds the month to the day, reduces that sum, reduces the year on its own, then adds the two; it also says that the day is never added to the year to obtain a master number (Taylor 1926 p. 56). This site keeps the same master stop but applies it to each of the three parts on its own — a reading of the stop, not the book's wording. The two readings part wherever the stop lands at a different point: for 29 November 2009 the book's way gives 11 + 29 = 40 → 4, then 4 + 11 = 15 → 6, while this site gives 11 + 11 + 11 = 33 → 33; for 18 February 2009 the book's 2 + 18 = 20 → 2 plus the year 11 gives 2 + 11 = 13 → 4, while this site gives 2 + 9 + 11 = 22 → 22. The common modern habit is a third reading: it adds every digit of the date in one pass and then reduces the total. On 28 April 1968 this site's rule gives 11, while the one-pass rule gives 38, then 11, then 2; Cafe Astrology prints that sequence (Cafe Astrology, Numerology).
| Date | Component rule (this site) | One-pass rule | Same final number? |
|---|---|---|---|
| 1872-07-04 | 7 + 4 + 9 = 20 → 2 | 2 | yes |
| 1968-04-28 | 4 + 1 + 6 = 11 → 11 | 2 | no |
| 2009-11-11 | 11 + 11 + 11 = 33 → 33 | 6 | no |
| 2024-02-29 | 2 + 11 + 8 = 21 → 3 | 3 | yes |
The order alone often changes only the intermediate sum: Coolidge's date reaches 2 either way. The visible disagreement needs the second rule, the master stop. That is why the two are worth reading together.
2. Where the master stop ends
Taylor's rule keeps 11 and 22 instead of reducing them to 2 and 4, "the master vibrations" (Taylor 1926 p. 23). A calculator that adds the whole date in one pass can still reduce the resulting 11 in the next step, as Cafe Astrology does with the 1968 example. The arithmetic is identical; the stopping point is not.
| Kept | If reduced |
|---|---|
| 11 | 2 |
| 22 | 4 |
| 33 | 6 |
Numerara keeps the master at every step: a month of 11, a day of 29, a word subtotal, a vowel sum and the final total all stop. The rule is stated in the reduction table on How we calculate.
3. Whether 33 counts
The 1926 handbook and Cafe Astrology name 11 and 22 only. Astrala's editorial page adds 33 and says the three master numbers do not reduce further (Astrala, Master Numbers). Numerara keeps 33, which is a modern extension of the rule. It is reachable: 11 November 2009 gives 11 + 11 + 11 = 33 under the component rule, and 15 → 6 under the one-pass rule.
The same page shows why the choice matters beyond one card. A reader who expects 33 will read 6 as an error, and a reader who expects 6 will read 33 as a calculator that refused to finish the sum. The site shows the boundary and says which rule produced it on Master numbers.
4. The letter Y
Y sits between the two groups, and traditions do not agree. Astrala's article gives the finer rule (Y is a vowel when it is preceded by another vowel or when there is no other vowel in the syllable), and its calculator counts the Y in Avery as a vowel (Astrala, Name Numerology). A strict consonant split gives a different pair of numbers from the same letters.
| Number | Y as a vowel (this site) | Y as a consonant |
|---|---|---|
| Expression | 3 | 3 |
| Soul Urge | 2 | 4 |
| Personality | 1 | 8 |
Only Soul Urge and Personality move: the Expression adds every letter, so the total is the same. Numerara always counts Y as a vowel, states the simplification next to the Soul Urge card, and explains the finer rule on Name numerology.
5. Which chart the name uses
Pythagorean and Chaldean values are different tables, not two names for one table. Cheiro's Chaldean chart has no 9 and gives different values to most letters (Cheiro 1926 p. 70). For David Wark Griffith the Pythagorean chart produces three name numbers; the Chaldean chart produces one.
| Number | Raw sum | Result |
|---|---|---|
| Pythagorean Expression | 95 | 5 |
| Pythagorean Soul Urge | 29 | 11 |
| Pythagorean Personality | 66 | 3 |
| Chaldean name number | 59 | 5 |
The Chaldean number also reduces a compound 22 to 4, with no master stop (Cheiro 1926 p. 71). That is not a mistake in the table: it is the older system's rule. The two charts side by side are on Pythagorean vs Chaldean.
What to do with the difference
None of these branches is a bug in the arithmetic; each one is a rule choice that a source states. The practical answer is to read the rule your source uses, then compare like with like. If a result here differs from another site, the table above usually names the branch responsible before you have to hunt for it. The rules this site applies, with page-level citations, are on How we calculate.