Principles of Hindu Reckoning (Kitab fi usul hisab al-hind) is a mathematics book written by 10th–11th-century Persian mathematician Kushyar ibn Labban

Kushyar ibn Labban

Abul-Hasan Kūshyār ibn Labbān ibn Bashahri Gilani , also known as Kūshyār Gīlānī , was a Persian mathematician, geographer, and astronomer from Gilan, south of the Caspian Sea, Iran....

. It is the second-oldest book extant in Arabic about Hindu arithmetic using Hindu numerals( ० ۱ ۲ ۳ ۴ ۵ ۶ ۷ ۸ ۹), preceded by Kibab al-Fusul fi al-Hisub al-Hindi by Abul al-Hassan Ahmad ibn Ibrahim al-Uglidis

Abu'l-Hasan al-Uqlidisi

Abu'l Hasan Ahmad ibn Ibrahim Al-Uqlidisi was an Arab mathematician who was active in Damascus and Baghdad. As his surname indicates, he was a copyist of Euclid's works. He wrote the earliest surviving book on the positional use of the Arabic numerals, Kitab al-Fusul fi al-Hisab al-Hindi around 952...

, written in 952. Although Al-Khwarzimi also wrote a book about Hindu arithmetics in 825, he did not use Hindu numerals, and the Arabic original was lost, only a 12th century translation is extant. Kushyar ibn Labban did not mention the Indian sources for Hindu Reckoning, and there is no earlier Indian book extant which covers the same topics as discussed in this book. Principles of Hindu Reckoning becomes one of the foreign sources for Hindu Reckoning in the 10th–11th century in India.

Indian dust board

Hindu arithmetic was conducted on a dust board similar to the Chinese counting board. A dust board is a flat surface with a layer of sand and lined with grids. Very much like the Chinese count rod numerals, a blank on a sand board grid stood for zero, and zero sign was not necessary.Shifting of digits involves erasing and rewriting, unlike counting board.

Content

There is only one Arabic copy extant, now kept in the Aya Sophya Library in Istanbul. There is also a Hebrew translation with commentary, kept in the Bodleian Library

Bodleian Library

The Bodleian Library , the main research library of the University of Oxford, is one of the oldest libraries in Europe, and in Britain is second in size only to the British Library...

 of Oxford University. In 1965 University of Wisconsin Press published an English edition of this book translated by Martin Levey and Marvin Petruck, based on both the Arabic and Hebrew editions. This English translation included 31 plates of facsimile of original Arabic text.

Principles of Hindu Reckoning consists of two parts dealing with arithmetics in two numerals system in India at his time.

• Part I mainly dealt with decimal algorithm of subtraction, multiplication, division, extraction of square root and cubic root in place value Hindu-numeral
  Hindu–Arabic numeral system
  The Hindu–Arabic numeral system or Hindu numeral system is a positional decimal numeral system developed between the 1st and 5th centuries by Indian mathematicians, adopted by Persian and Arab mathematicians , and spread to the western world...
  
   system. However, a section on "halving", was treated differently, i.e., with a hybrid of decimal and sexagesimal numeral.

The similarity between decimal Hindu algorithm with Chinese algorithm in Mathematical Classic of Sun Zi are striking, except the operation halving, as there was no hybrid decimal/sexagesimal calculation in China.

• Part II dealt with operation of subtraction, multiplication, division, extraction of square root and cubic root in sexagesimal number system. There was only positional decimal arithmetic in China, never any sexagesimal arithmetic.
• Unlike Abu'l-Hasan al-Uqlidisi
  Abu'l-Hasan al-Uqlidisi
  Abu'l Hasan Ahmad ibn Ibrahim Al-Uqlidisi was an Arab mathematician who was active in Damascus and Baghdad. As his surname indicates, he was a copyist of Euclid's works. He wrote the earliest surviving book on the positional use of the Arabic numerals, Kitab al-Fusul fi al-Hisab al-Hindi around 952...
  
  's Kitab al-Fusul fi al-Hisab al-Hindi (The Arithmetics of Al-Uqlidisi) where the basic mathematical operation of addition, subtraction, multiplication and division were described in words, ibn Labban's book provided actual calculation procedures expressed in Hindu-Arabic numerals.

Addition

Kushyar ibn Labban described in detail the addition of two numbers.

The Hindu addition is identical to rod numeral addition in Mathematical Classic of Sun Zi

operation	Rod calculus	Hindu rekoning
Layout	Arrange two numbers in two rows	Arrange two numbers in two rows
order of calculation	from left to right	from left to right
result	placed on top row	Placed on top row
remove lower row	remove digit by digit from left to right	digit not removed

There was a minor difference in the treatment of second row, in Hindu reckoning, the second row digits drawn on sand board remained in place from beginning to end, while in rod calculus, rods from lower rows were physically removed and add to upper row, digit by digit.

Subtraction

In the 3rd section of his book, Kushyar ibn Labban provided step by step algorithm for subtraction of 839 from 5625. Second row digits remained in place at all time. In rod calculus, digit from second row was removed digit by digit in calculation, leaving only the result
in one row.

Multiplcation

Kushyar ibn Labban multiplication is a variation of Sun Zi mulitiplication.

operation	Sun Zi	Hindu
multiplicant	placed at upper row,	placed at upper row,
multiplier	third row	2nd row below multiplicant
alignment	last digit of multiplier with first digit of multiplcant	last digit of multiplier with first digit of multiplcant
multiplyier padding	rod numeral blanks	rod numeral style blanks, not Hindu numeral 0
order of calculation	from left to right	from left to right
product	placed at center row	merged with multiplicant
shifiting of multiplier	one position to the right	one position to the right

Division

Professor Lam Lay Yong

Lam Lay Yong

Lam Lay Yong , granddaughter of Tan Kah Kee, niece of Lee Kong Chian, is Professor in Mathematics at the Department of Mathematics, National University of Singapore. She graduated from the National University of Singapore in 1957 and pursued graduate study in Cambridge University, obtaining her Ph.D...

 discovered that the Hindu division method describe by Kushyar ibn Labban is totally identical to rod calculus division in 5th centuryMathematical Classic of Sun Zi

operation	Sun Zi division	Hindu division
dividend	on middle row,	on middle row,
divisor	divisor at bottom row	divisor at bottom row
Quotient	placed at top row	placed at top row
divisor padding	rod numeral blanks	rod numeral style blanks, not Hindu numeral 0
order of calculation	from left to right	from left to right
Shifting divisor	one position to the right	one position to the right
Remainder	numerator on middle row,denominator at bottom	numerator on middle row,denominator at bottom

Besides the totally identical format, procedure and remainder fraction, one tell tell sign which discloses the origin of this division algorithm is in the missing 0 after 243, which in true Hindu numeral should be written as 2430, not 243blank; blank space is a feature of rod numerals (and abacus).

Divide by 2

Divide by 2 or "halving" in Hindu reckoning was treated with a hybrid of decimal and sexagesimal numerals:
It was calculated not from left to right as decimal arithmetics, but from right to left:
After halving the first digit 5 to get 2, replace the 5 with 2, and write 30 under it:

5622

30

Final result:

2812

30

Extraction of square root

Kushyar ibn Labban described the algorithm for extraction of square root with example of



Kushyar ibn Labban square root extraction algorithm is basically the same as Sun Zi algorithm

operation	Sun Zi square root	ibn Labban sqrt
dividend	on middle row,	on middle row,
divisor	divisor at bottom row	divisor at bottom row
Quotient	placed at top row	placed at top row
divisor padding	rod numeral blanks	rod numeral style blanks, not Hindu numeral 0
order of calculation	from left to right	from left to right
divisor doubling	multiplied by 2	multiplied by 2
Shifting divisor	one position to the right	one position to the right
Shifting quotient	Positioned at beginning, no subsequent shift	one position to the right
Remainder	numerator on middle row,denominator at bottom	numerator on middle row,denominator at bottom
final denominator	no change	add 1

The approximation of non perfect square root using Sun Zi algorithm yields result slightly higher than the true value in decimal part, the square root approximation of Labban gave slightly lower value, the integer part are the same.

Multiplication

The Hindu sexagesimal multiplication format was completely different from Hindu decimal arithmetics. Kushyar ibn Labban's example
of 25 degree 42 minutes multiplied by 18 degrees 36 minutes was written vertically as

18| |25

36| |42

with a blank space in between

Influence

Kushyar ibn Labban's Principles of Hindu Reckoning exerted strong influence on later Arabic algorists. His student al-Nasawi followed his teacher's method. Thirteen century algorist Jordanus nemorarius

Jordanus Nemorarius

Jordanus de Nemore was a thirteenth-century European mathematician who wrote treatises on at least 6 different important mathematical subjects: the science of weights; “algorismi” treatises on practical arithmetic; pure arithmetic; algebra; geometry; and stereographic projection. Most of these...

's work was influenced by al-Nasawi. As late as 16th century, ibn Labban's name was still mentioned

External links

• The Development of Hindu-Arabic and Traditional Chinese Arithematics, Chinese Science 13 1996, 35-54