# Egyptian multiplication and division

Since the 1880s an incomplete and muddled view defined ancient Egyptian multiplication and division operations  . http://eom.springer.de/A/a013260.htmSpringer’s on-line encyclopedia summarizes a 1920s view on http://en.wikipedia.org/wiki/Egyptian_multiplication_and_divisionWikpedia:

The art of computation arose and developed before the time of the oldest written records. The oldest advanced mathematical records include the Kahun (Cahoon) papyri and the famous Rhind papyrus, which, among other papyri, date to 2050 BCE. Earlier additive  hieroglyphic arithmetic  methods represented numbers in ways that Old Kingdom Egyptians performed addition  and subtraction operations in relatively simple ways. For example, multiplication was carried out by doubling, i.e. the factors were decomposed into sums of powers of two, the individual summands were multiplied, and the components added. Operations on fractions were reduced in Ancient Egypt to operations on aliquot fractions. More complicated fraction operations were decomposed with the aid of tables as the sums of aliquot fractions.

In 1862 the first Egyptian text, the Berlin Papyrus, was published. Formal scholarly solutions appeared in 1900 with the work of Schack-Shackenberg. European scholars did not consider the Berlin Papyrus when 1920s transliterations of the RMP were published in incomplete additive versions of Egyptian multiplication. The 1920s historians had also not followed up a 1895 report (by F. Hultsch) that suggested a second form of multiplication method was present in Ahmes’ 2/n table, and other RMP problems (i.e. RMP 38). The second method included aliquot parts, as Springer suggests above.

Ahmes’ aliquot part division steps, sensed in the 19th century, were not decoded during the 20th century for several reasons. Two reasons misdirected 1920s math historians by considering transliterations rather than translations. The first class of reason prematurely closed the subject of Egyptian fraction       arithmetic operations by concluding Egyptian multiplication contained only additive steps. The Second class of reason scribal division was suggested have followed an non-inverse process called ’single false position’, or ’trial and error’ reported by scholars related to RMP 24-35, Ahmes’ algebra  problems.

The aliquot part story line remained unsolved until 2008. Shortly after 2002 the http://planetmath.org/encyclopedia/KahunPapyrusAndArithmeticProgressions.htmlKahun Papyrus and the http://rmprectotable.blogspot.com/Rhind Papyrus 2/n table were decoded revealing two aliquot part operational methods: (1) new inverse    multiplication and division methods, and (2) a LCM number method written in red. The multiplication and division methods had been hidden in same set of aliquot part operational steps, including http://planetmath.org/encyclopedia/FirstLCMMethodRedAuxiliaryNumbers.htmlred auxiliary numbers steps. In 2006, the 1895 Hultsch-Bruins method was confirmed from a second direction, detailing a common aliquot method used in the RMP and Egyptian Mathematical Leather Roll  , and published on-line in 2008.

Springer’s summary of Egyptian multiplication and division followed the misleading 1920s definition of Egyptian division suggesting: ”Division was carried out by subtracting from the number to be divided the numbers obtained by successive doubling of the divisor.” Math historians from 1920 to 1990 (i.e.; Howard Eves) called the proposed Egyptian division method ’single false position’, and 1990 scholars (i.e. Spalinger) called the scribal information ’trial and error’. Ironically, ’single false position’ was first documented in 800 AD, and at no earlier data. Later Arab texts improved up its root finding ’double http://en.wikipedia.org/wiki/False_positionfalse position ’, method. ’Trial and error’ in Ahmes’ algebra problems selected LCM m to scale rational numbers n/p to mn/pm, and therefore can not be a scribal division fragment.

Springer’s definition of Egyptian division was historically incomplete on several levels. A complete    definition of Egyptian scribal division should include discussion of the first six RMP problems. RMP 1-6 reported division by 10 labor rates defined in the http://planetmath.org/encyclopedia/ReisnerPapyrus.htmlReisner Papyrus. In addition, RMP algebra problems and methods are consulted. For example, Ahmes divided 28 by 97, in http://mathforum.org/kb/thread.jspa?threadID=1768698&tstart=0RMP 31(confirmed in RMP 34) by solving: x + (2/3 + 1/2 + 1/7)x = 33 and x + (2/3 + 1/2 + 1/7)x = 37 as other vulgar fraction problems were solved in the Kahun Papyrus and Rhind Papyrus 2/n tables. Aliquot part steps were hidden in theoretical multiplication and division operations for over 100 years.

Ahmes, therefore, did not use ’single false position’ in any arithmetic operation, a point made by Robins-Shute in 1987. The 1920s ’false position’ and 1990 ’trial and error’ scholarly ideas were false suppositions. For example, 28/97, in RMP 31, and data from RMP 21- 23 expose Ahmes’ LCM method. In RMP 23 where 45 was introduced solving most of the problem, but 360 was needed to Ahmes to complete the problem as all other algebra problems were solved.

In the 21st century, Ahmes is being reported converting vulgar fractions into optimized unit fractions series within a LCM m multiplication method. The LCM method replaced the aliquot parts of the denominator in the numerator. To convert 2/97 in RMP 31, and the 2/n table. Ahmes converted 28/97 into two problems, 2/97 and 26/97, such that:

1. To convert 2 by 97: As Ahmes’ 2/n table wrote for all 2/n conversions less than 2/101, he first selected a highly divisible number m as an optimizing multiplier m/m. In the 2/97 case 56 was selected, creating a multiplier 56/56 such that the aliquot parts of 56 (28, 14, 8, 7, 4, 2, 1) were introduced into the solution by writing:

2/97*(56/56) = 112/(56*97) = (97 + 8 + 7)/56*97)

and,

2/97 = 1/56 + 1/679 + 1/776

2. To convert 26/97 Ahmes looked for a multiplier m/m that would increase the numerator to greater than 97. Ahmes found 4/4. By considering the aliquot parts of 4 (4 , 2, 1) Ahmes wrote out:

26/97*(4/4) = 104/(4*97)= (97 + 4 + 2 + 1)/(4*97)

such that:

26/97 = 1/4 + 1/97 + 1/194 + 1/388

and,

3. Ahmes combined steps 2/97 and 26/97 into one Egyptian fraction series by writing:

28/97 = 1/4 + 1/56 + 1/97 + 1/194 + 1/388 + 1/679 + 1/77

’Single false position’ was false 20th century supposition that failed to parse Ahmes’ actual division operation. Ahmes division operation is correctly parsed as inverse to Egyptian multiplication. Egyptian scribes applied theoretical ideas in http://planetmath.org/encyclopedia/AnOverViewOfAhmesPapyrus.htmlAhmes math tool box to convert rational numbers to Egyptian fractions.

8 + 280/365

the expected daily use of fat.

The quotient 8 was proven by the binary steps 1 - 365, 2 - 730, 4 - 1460, and 8 - 2920. The remainder 280 (3200 - 2920 = 280). Translated to modern notation Ahmes’ proof multiplied the initial divisor 365 by (8 + 2/3 + 1/10 + 2190) summing (2920 + 243 1/3 + 36 1/2 + 1/6) obtaining 3200 ro, the exact initial value of 10 hekat of fat.

RMP 38 reported Ahmes multiplying 320 ro, one hekat, by 7/22, obtaining 101 9/11. The 101 9/11 answer was proven by multiplying 101 9/11 by 22/7, with the initial divisor 7/22 parsed by binary steps 34/11 times 1/10 = 7/22 showing that inverse multipliers define division, one of several modern arithmetic ideas that were anticipated by Ahmes.

Conclusion  : To parse ancient Egyptian multiplication and division written with a weights and measures context , Ahmes’ 2/n table and other arithmetic operations must be stripped away to reveal rational numbers. Ahmes multiplication and division of rational numbers were inverse to each other.

Egyptian multiplication contained two aspects, a theoretical side, and a practical side. Egyptian division was an inverse of Egyptian multiplication, and visa verse. Prior to the 21st century AD Egyptian math scholars had not considered theoretical aspects of the RMP and other Egyptian texts. Theoretical definitions hid an aliquot part and other arithmetic definitions, two being a hekat unity stated as (64/64), and a hekat stated as 320 ro. Egyptian division was quotient and exact remainder based, aspects that scholars are increasingly studying, linked to aliquot parts, 2/n tables, and other ancient scribal applications, such as weights and meaures, after 2005.

Title Egyptian multiplication and division EgyptianMultiplicationAndDivision 2013-03-22 18:28:42 2013-03-22 18:28:42 milogardner (13112) milogardner (13112) 67 milogardner (13112) Definition msc 01A16