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Some traditions say, based on a Gemmorah in Taanis 9a (also מדרש רבה נשא י' ו', זוהר פנחס רכ"א א, and more):

"ליכא מידי דלא רמיזא באורייתא"

"There is nothing that is not alluded to in the Torah"

That is, everything can be derived from the written Torah (the Pentateuch of 304,805 letters, and Gr"a adds from Parashat Bereshis alone etc). Many tried (and succeeded) to find certain integers, such as numbers and dates.

In what way can the irrational and infinite number Pi be derived from the written Torah?

(to clarify, the question is not about approximation of Pi, it is about the possibility to derive an irrational number from a list of letters)

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    Just because it can be done in principle doesn't mean anyone knows how to do it in practice.
    – Heshy
    Commented Jul 30, 2018 at 5:38
  • Are you accepting answers from Nach? In that case it’s trivial - the Gemara already discusses it.
    – DonielF
    Commented Jul 30, 2018 at 5:39
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    @DonielF well, math textbooks define it in a finite number of characters.
    – Heshy
    Commented Jul 30, 2018 at 7:02
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    Gemara Eruvin. Pi was not irrational in theire mind. The discovery of rational-irrational concept is posterior
    – kouty
    Commented Jul 30, 2018 at 11:37
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    Just because PI is irrational (and even transcendental), doesn't mean you cannot describe it accurately in a finite number of syllables. Just as an example, there are numerous infinite series that converge to Pi. E.g. en.wikipedia.org/wiki/Leibniz_formula_for_%CF%80
    – Nic
    Commented Jul 30, 2018 at 14:11

4 Answers 4

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Pi can be derived from the Torah by rolling up a Torah scroll and measuring the end's diameter and circumference. The ratio between them will be pi.

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    No joke! See Bava Batra 14a
    – Double AA
    Commented Jul 30, 2018 at 11:41
  • it is about the possibility to derive an irrational number from a list of letters - I guessed he asked for it! :-D Commented Jul 30, 2018 at 11:59
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    Technically this would be a linear spiral, but you have my upvote.
    – Nic
    Commented Jul 30, 2018 at 14:08
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    Hah! One of the great Ma'asei Hashem! No matter who rolls a Torah, no matter how loosely or tightly it's rolled and no matter what the sixe of the Torah is, you get the same number by dividing the circumference by its diameter. Seems like a nes (miracle) to me! Who needs Euclid?
    – DanF
    Commented Jul 30, 2018 at 14:23
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    This answer is being discussed on meta. Commented Jan 21, 2019 at 17:40
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The Vilna Gaon saw that the word “line” in the parallel Kings and Chronicles texts of the passage are spelled קוה and קו respectively. The extra ה is the key.

Take the ratio of the sums of the standard numeric values of the Hebrew letters (kuf = 100, vav = 6,Hey = 5) for each of these words, obtaining 111/106; multiply by 3 – the apparent value of π and we obtain π is equal to 333/106 ≈ 3.141509, agreeing with π to four decimal digits.

This article also finds pi using gematria Genesis and pi

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    This answer is good because this is an allusion to the actual irrational number pi. But it's also bad because of the clause "the question is not about approximation of Pi, it is about the possibility to derive an irrational number from a list of letters". Either way, thanks for joining Mi Yodeya, welcome!
    – Rabbi Kaii
    Commented Jul 25 at 16:43
  • It's an amazing calculation. I can't understand what the point of multiplying by 3 is, even if 3 is the approximation mentioned in the passuk. Can anyone explain this?
    – chortkov2
    Commented Jul 25 at 20:57
  • @chortkov2 you can think of it like this: the pasuk in Kings I 7:23 gives a ratio of pi that is 3, and that is because the diamter is 10 and the circumference is 30. Vilna Gaon is explaining how to adjust the given circumference of 30 to 31.415 [by multiplying by the ratio of 111/106 which I bet is exactly what Shlomo got with his measuring tools :)]
    – Rabbi Kaii
    Commented Jul 25 at 22:39
  • look at the ralbag there were he explains it as exact and not an estimate. iirc he proposes that the inner circumference was 30 and the diameter from the outer edges was 10
    – Mordechai
    Commented Jul 26 at 0:13
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Pi is computable, i.e. it can be defined using finite rules, and those rules explain a set of infinite steps that can be followed, and the limit of those steps is pi.

This proves that there is no inherent issue with the Torah being "composed of letters" as a barrier to it containing the definition of pi* (and what is wrong with the geometrical definition of pi?), and maybe isn't any better than asking how is a googol or Graham's number alluded to in the Torah?

One could imagine such a set of rules exists in the Torah, one day to be discovered or revealed, but it is clear we don't have that information at the moment. Not that that matters much.

[What might be a better question is how are the non-computable numbers found in the Torah?]

* Mādhava of Sangamagrāma, who wrote the most famous series expansion for pi, wrote the steps in verse

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  • no conceivable practical use? Being able to compute the busy beaver function for example, would let us decide the halting problem, and that's amazingly useful (e.g. we'd be able to instantly prove Godlbach's conjecture, etc).
    – user9806
    Commented Jul 25 at 17:55
  • @user9806 thanks, I either didn't know that, or I forgot it!
    – Rabbi Kaii
    Commented Jul 25 at 18:02
  • Brilliant, thank you.
    – Al Berko
    Commented Jul 25 at 20:26
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There are claims that already in the old kingdom of Egypt everybody used approximation of pi as 22/7 = 3.142857. For sure, it was known at the time of Archimedes. Hebrew alphabet has 22 letters and 7 is the number of the original double letters בגד כפרת according to Sefer Yetzira. In the commentary to the translation by Arieh Kaplan, it states the sound of resh with dagesh was lost or deliberately concealed (1). So pi is alluded by a reciprocal of a fraction of double letters, which themselves hint to rolling/repetition of the alphabet to invoke a second sound.

Alternatively, 7 is the number of days in a week. Incidentally, these are the first two complete quantities defined by the Torah, which brings the question, what can be learned from it?


(1) Quote from Aryeh Kaplan "Sefer Yetzira", Revised edition, Weiser, 1997, p. 160 (the book provides a big list of original sources):

Highly significant is the fact that the Resh (ר) is considered one of the doubles. Most post-Talmudic grammarians take presently the opposite view, and state that the Resh never take a Dagesh. Not only is there no verbal distinction between the hard and soft Resh, but modern Hebrew grammar does not even recognize such a difference in the written form.

There are, however ten different words, appearing in fourteen places in the Bible, which are written with a Resh containing a Dagesh.

See Table 28, containing: 1. haRimah Shmuel A 1:6, 2. haR'item Shmuel A 10:24, 17:25, Melachim B 6:32; 3. Ra Yirmiyahu 39:12, Mishlei 11:21, 20:22; 4. Karat Yechezkel 16:4; 5. Sharekh Yechezkel 16:4; 6. Rosh Habakuk 3:13; 7. LeSharekha Mishlei 3:8; 8. Marat Mishlei 14:10; 9. Rakh Mishlei 15:1; 10. sheRoshi Shir haShirim 5:2.

It is obvious, however that the usual rules applying to letters בגד כפת, do not apply to Resh.

The present sound of Resh is a fricative, and and is therefore most probably the soft sound. The hard Resh was either lost or deliberately concealed after destruction of the Temple. In earlier times, its use was standard, and there is evidence from their transliteration of names, that its pronunciation was known to the authors of the Septuagint (which used double for Sarrah). By the 10th century, however the double Resh was only used by the members of the small Mazya community in Tiberias. Tiberias had been the last city in which the Sanhedrin, the great court which preserved the tradition, had flourished. This was one of the mysteries that the Sanhedrin had entrusted to the community of Tiberias.

According to the Sefer Yetsira 2:3, Resh is in the group of Dentals (זסשרצ). Alon with letters Zayin, Samekh, SHin, Tzadi, it is pronounced with teeth. According to Long Version (of Sefer Yetsira) 2:1, it is sounded "between teeth with the tongue lying down, spread out." We cannot say that it is a rolled /r/ sound, since this involves the tip of the tongue. It would then be closest to the /l/ sound, and should be included among the Linguals (דטלנת). Furthermore, the hard Resh should be a plosive, like all other hard doubles.

There is no /r/ sound in use today that meets these criteria. Furthermore, there is no plosive sound pronounced with the teeth that could be a candidate for the hard Resh. The original pronunciation of this letter therefore remains a mystery.

Some people believe that pronunciation of /ř/ in Czech language as well as /rz/ in Polish language is the original pronunciation of Resh with dagesh.

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  • Thank you, very insightful. You only need to explain why dividing the number of letters by the number of days in a week gives you the circumference. Did you read Kaii's answer?
    – Al Berko
    Commented Jul 25 at 21:56
  • @AlBerko 22 and 7 are first two numbers defined by the Torah, the Alphabet and Shabbat. Maybe to show that the Creation is round? That's a fantastic and very deep qestion by itself.
    – Y DJ
    Commented Jul 25 at 22:29
  • Interestingly, the alphabet is not "hardcoded" in the Torah, and Shabbos doesn't appear before Exodus.
    – Al Berko
    Commented Jul 26 at 8:22
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    Very intriguing answer. Can you please expand on the part about the Sanhedrin forbidding רּ?
    – Qwertrl
    Commented Aug 21 at 15:20
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    @QwertyCTRL. The comment is added. Perhaps one can ask a separate question about Resh with a Dagesh? I made a mistake earlier (wrote by memory instead of looking in a book). It only says that the sound "was either lost or deliberately concealed."
    – Y DJ
    Commented Aug 21 at 17:35

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