Greek numerals

Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the

Greek alphabet

. In modern

Greece

, they are still used for ordinal numbers and in contexts similar to those in which Roman numerals are still used in the

Western world

. For ordinary cardinal numbers, however, modern Greece uses

Arabic numerals

.

History

The Minoan and Mycenaean civilizations' Linear A and Linear B alphabets used a different system, called Aegean numerals, which included number-only symbols for powers of ten:  = 1,  = 10,  = 100,  = 1000, and  = 10000.

Attic numerals comprised another system that came into use perhaps in the 7th century . They were acrophonic, derived (after the initial one) from the first letters of the names of the numbers represented. They ran  = 1,  = 5,  = 10,  = 100,  = 1,000, and  = 10,000. The numbers 50, 500, 5,000, and 50,000 were represented by the letter with minuscule powers of ten written in the top right corner: , , , and . One-quarter was represented by (right half of a full circle) and one-half by the left side of the circle. The same system was used outside of

Attica

, but the symbols varied with the local alphabets, for example, 1,000 was in

Boeotia

.

The present system probably developed around Miletus in Ionia. 19th century classicists placed its development in the 3rd century , the occasion of its first widespread use. More thorough modern archaeology has caused the date to be pushed back at least to the 5th century , a little before Athens abandoned its pre-Euclidean alphabet in favour of Miletus's in 402 , and it may predate that by a century or two. The present system uses the 24 letters used by Euclid, as well as three

Phoenician

and Ionic ones that had not been dropped from the Athenian alphabet (although kept for numbers): digamma, koppa, and sampi. The position of those characters within the numbering system imply that the first two were still in use (or at least remembered as letters) while the third was not. The exact dating, particularly for

sampi

, is problematic since its uncommon value means the first attested representative near Miletus does not appear until the 2nd century , and its use is unattested in Athens until the 2nd century . (In general, Athenians resisted using the new numerals for the longest of any Greek state, but had fully adopted them by .)

Description

Greek numerals are decimal, based on powers of 10. The units from 1 to 9 are assigned to the first nine letters of the old Ionic alphabet from alpha to theta. Instead of reusing these numbers to form multiples of the higher powers of ten, however, each multiple of ten from 10 to 90 was assigned its own separate letter from the next nine letters of the Ionic alphabet from iota to koppa. Each multiple of one hundred from 100 to 900 was then assigned its own separate letter as well, from rho to sampi. (That this was not the traditional location of sampi in the Ionic alphabetical order has led classicists to conclude that sampi had fallen into disuse as a letter by the time the system was created.)

This alphabetic system operates on the additive principle in which the numeric values of the letters are added together to obtain the total. For example, 241 was represented as  (200 + 40 + 1). (It was not always the case that the numbers ran from highest to lowest: a 4th-century BC inscription at Athens placed the units to the left of the tens. This practice continued in

Asia Minor

well into the Roman period.Heath, Thomas L. ''A Manual of Greek Mathematics''
pp. 14 ff.
Oxford Univ. Press (Oxford), 1931. Reprinted Dover ( Mineola), 2003. Accessed 1 November 2013.) In ancient and medieval manuscripts, these numerals were eventually distinguished from letters using overbars: , , , etc. In medieval manuscripts of the Book of Revelation, the number of the Beast 666 is written as  (600 + 60 + 6). (Numbers larger than 1,000 reused the same letters but included various marks to note the change.) Fractions were indicated as the denominator followed by a ''keraia'' (ʹ); γʹ indicated one third, δʹ one fourth and so on. As an exception, special symbol ∠ʹ indicated one half, and γ°ʹ or γoʹ was two-thirds. These fractions were additive (also known as Egyptian fractions); for example indicated .

Although the Greek alphabet began with only majuscule forms, surviving

papyrus

manuscripts from

Egypt

show that

uncial

and

cursive

minuscule forms began early. These new letter forms sometimes replaced the former ones, especially in the case of the obscure numerals. The old Q-shaped koppa (Ϙ) began to be broken up ( and ) and simplified ( and ). The numeral for 6 changed several times. During antiquity, the original letter form of digamma (Ϝ) came to be avoided in favour of a special numerical one (). By the Byzantine era, the letter was known as episemon and written as or . This eventually merged with the sigma-tau ligature stigma ϛ ( or ).

In modern Greek, a number of other changes have been made. Instead of extending an over bar over an entire number, the ''keraia'' (, lit. "hornlike projection") is marked to its upper right, a development of the short marks formerly used for single numbers and fractions. The modern ''keraia'' () is a symbol similar to the

acute accent

(´), the

tonos

(U+0384,΄) and the prime symbol (U+02B9, ʹ), but has its own

Unicode

character as U+0374.

Alexander the Great

's father Philip II of Macedon is thus known as in modern Greek. A lower left ''keraia'' (Unicode: U+0375, "Greek Lower Numeral Sign") is now standard for distinguishing thousands: 2019 is represented as ͵ΒΙΘʹ ().

The declining use of ligatures in the 20th century also means that stigma is frequently written as the separate letters ΣΤʹ, although a single ''keraia'' is used for the group.

Isopsephy (gematria)

The art of assigning Greek letters also being thought of as numerals and therefore giving words, names and phrases a numeric sum that has meaning through being connected to words, names and phrases of similar sum is called isopsephy (gematria). No

Table

* Alternatively, sub-sections of manuscripts are sometimes numbered by lowercase characters (αʹ. βʹ. γʹ. δʹ. εʹ. ϛʹ. ζʹ. ηʹ. θʹ.).
* In Ancient Greek, myriad notation is used for multiples of 10,000, for example for 20,000 or (also written on the line as Μ ) for 1,234,567.Greek number systems - MacTutor
/ref>

Higher numbers

In his text ''The Sand Reckoner'', the natural philosopher

Archimedes

gives an upper bound of the number of grains of sand required to fill the entire universe, using a contemporary estimation of its size. This would defy the then-held notion that it is impossible to name a number greater than that of the sand on a beach or on the entire world. In order to do that, he had to devise a new numeral scheme with much greater range.

Pappus of Alexandria reports that Apollonius of Perga developed a simpler system based on powers of the myriad; was 10,000, was 10,000² = 100,000,000, was 10,000³ = 10¹² and so on.

Zero

Hellenistic

astronomer

s extended alphabetic Greek numerals into a sexagesimal positional numbering system by limiting each position to a maximum value of 50 + 9 and including a special symbol for

zero

, which was only used alone for a whole table cell, rather than combined with other digits, like today's modern zero, which is a placeholder in positional numeric notation. This system was probably adapted from

Babylonian numerals

by Hipparchus . It was then used by Ptolemy (), Theon () and Theon's daughter Hypatia (died 415). The symbol for zero is clearly different from that of the value for 70,

omicron

or "

ο

". In the 2nd-century papyrus shown here, one can see the symbol for zero in the lower right, and a number of larger omicrons elsewhere in the same papyrus.

In Ptolemy's table of chords, the first fairly extensive trigonometric table, there were 360 rows, portions of which looked as follows:

: $\begin \pi\varepsilon\varrho\iota\varphi\varepsilon\varrho\varepsilon\iota\tilde\omega\nu & \overset\varepsilon\nu\vartheta\varepsilon\iota\tilde\omega\nu & \overset\varepsilon\xi\eta\kappa\omicron\sigma\tau\tilde\omega\nu \\ \begin \hline \pi\delta\angle' \\ \pi\varepsilon \\ \pi\varepsilon\angle' \\ \hline \pi\stigma \\ \pi\stigma\angle' \\ \pi\zeta \\ \hline \end & \begin \hline \pi & \mu\alpha & \gamma \\ \pi\alpha & \delta & \iota\varepsilon \\ \pi\alpha & \kappa\zeta & \kappa\beta \\ \hline \pi\alpha & \nu & \kappa\delta \\ \pi\beta & \iota\gamma & \iota\vartheta \\ \pi\beta & \lambda\stigma & \vartheta \\ \hline \end & \begin \hline \circ & \circ & \mu\stigma & \kappa\varepsilon \\ \circ & \circ & \mu\stigma & \iota\delta \\ \circ & \circ & \mu\stigma & \gamma \\ \hline \circ & \circ & \mu\varepsilon & \nu\beta \\ \circ & \circ & \mu\varepsilon & \mu \\ \circ & \circ & \mu\varepsilon & \kappa\vartheta \\ \hline \end \end$
Each number in the first column, labeled is the number of degrees of arc on a circle. Each number in the second column, labeled is the length of the corresponding chord of the circle, when the diameter is 120. Thus represents an 84° arc, and the ∠′ after it means one-half, so that πδ∠′ means °. In the next column we see  , meaning That is the length of the chord corresponding to an arc of ° when the diameter of the circle is 120 . The next column, labeled for "sixtieths", is the number to be added to the chord length for each 1° increase in the arc, over the span of the next 12°. Thus that last column was used for

linear interpolation

.

The Greek sexagesimal placeholder or zero symbol changed over time: The symbol used on

papyri

during the second century was a very small circle with an overbar several diameters long, terminated or not at both ends in various ways. Later, the overbar shortened to only one diameter, similar to the modern ''o''-macron (ō) which was still being used in late medieval Arabic manuscripts whenever alphabetic numerals were used. But the overbar was omitted in

Byzantine

manuscripts, leaving a bare ''ο'' (omicron). This gradual change from an invented symbol to ''ο'' does not support the hypothesis that the latter was the initial of meaning "nothing". Note that the letter ''ο'' was still used with its original numerical value of 70; however, there was no ambiguity, as 70 could not appear in the fractional part of a sexagesimal number, and zero was usually omitted when it was the integer.

Some of Ptolemy's true zeros appeared in the first line of each of his eclipse tables, where they were a measure of the angular separation between the center of the

Moon

and either the center of the

Sun

(for

solar eclipse

s) or the center of

Earth

's shadow (for

lunar eclipse

s). All of these zeros took the form , where Ptolemy actually used three of the symbols described in the previous paragraph. The vertical bar (, ) indicates that the integral part on the left was in a separate column labeled in the headings of his tables as ''digits'' (of five arc-minutes each), whereas the fractional part was in the next column labeled ''minute of immersion'', meaning sixtieths (and thirty-six-hundredths) of a digit.

See also

*Attic numerals
*Cyrillic numerals
* Greek numerals in Unicode (acrophonic, not alphabetic, numerals)
*Isopsephy
*Number of the Beast
*Alphabetic numeral system

References

External links

The Greek Number Converter

{{DEFAULTSORT:Greek Numerals
Numeral systems
Numerals
Numerals