Multiplication table

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Multiplication table from 1 to 10 drawn to scale with the upper-right half labeled with prime factorisations Multiplication table to scale.svg
Multiplication table from 1 to 10 drawn to scale with the upper-right half labeled with prime factorisations

In mathematics, a multiplication table (sometimes, less formally, a times table) is a mathematical table used to define a multiplication operation for an algebraic system.

Contents

The decimal multiplication table was traditionally taught as an essential part of elementary arithmetic around the world, as it lays the foundation for arithmetic operations with base-ten numbers. Many educators believe it is necessary to memorize the table up to 9 × 9. [1]

History

Pre-modern times

The Tsinghua Bamboo Slips, Chinese Warring States era decimal multiplication table of 305 BC Qinghuajian, Suan Biao.jpg
The Tsinghua Bamboo Slips, Chinese Warring States era decimal multiplication table of 305 BC

The oldest known multiplication tables were used by the Babylonians about 4000 years ago. [2] However, they used a base of 60. [2] The oldest known tables using a base of 10 are the Chinese decimal multiplication table on bamboo strips dating to about 305 BC, during China's Warring States period. [2]

"Table of Pythagoras" on Napier's bones PSM V26 D467 Table of pythagoras on slats.jpg
"Table of Pythagoras" on Napier's bones

The multiplication table is sometimes attributed to the ancient Greek mathematician Pythagoras (570–495 BC). It is also called the Table of Pythagoras in many languages (for example French, Italian and Russian), sometimes in English. [4] The Greco-Roman mathematician Nichomachus (60–120 AD), a follower of Neopythagoreanism, included a multiplication table in his Introduction to Arithmetic , whereas the oldest surviving Greek multiplication table is on a wax tablet dated to the 1st century AD and currently housed in the British Museum. [5]

In 493 AD, Victorius of Aquitaine wrote a 98-column multiplication table which gave (in Roman numerals) the product of every number from 2 to 50 times and the rows were "a list of numbers starting with one thousand, descending by hundreds to one hundred, then descending by tens to ten, then by ones to one, and then the fractions down to 1/144." [6]

Modern times

In his 1820 book The Philosophy of Arithmetic, [7] mathematician John Leslie published a multiplication table up to 1000 × 1000, which allows numbers to be multiplied in pairs of digits at a time. Leslie also recommended that young pupils memorize the multiplication table up to 50 × 50.

The illustration below shows a table up to 12 × 12, which is a size commonly used nowadays in English-world schools.

×123456789101112
1123456789101112
224681012141618202224
3369121518212427303336
44812162024283236404448
551015202530354045505560
661218243036424854606672
771421283542495663707784
881624324048566472808896
9918273645546372819099108
10102030405060708090100110120
11112233445566778899110121132
121224364860728496108120132144

Because multiplication of integers is commutative, many schools use a smaller table as below. Some schools even remove the first column since 1 is the multiplicative identity.[ citation needed ]

11
224
3369
4481216
5510152025
661218243036
77142128354249
8816243240485664
991827364554637281
×123456789

The traditional rote learning of multiplication was based on memorization of columns in the table, arranged as follows.

0 × 0 = 0
1 × 0 = 0
2 × 0 = 0
3 × 0 = 0
4 × 0 = 0
5 × 0 = 0
6 × 0 = 0
7 × 0 = 0
8 × 0 = 0
9 × 0 = 0
10 × 0 = 0
11 × 0 = 0
12 × 0 = 0

0 × 1 = 0
1 × 1 = 1
2 × 1 = 2
3 × 1 = 3
4 × 1 = 4
5 × 1 = 5
6 × 1 = 6
7 × 1 = 7
8 × 1 = 8
9 × 1 = 9
10 × 1 = 10
11 × 1 = 11
12 × 1 = 12

0 × 2 = 0
1 × 2 = 2
2 × 2 = 4
3 × 2 = 6
4 × 2 = 8
5 × 2 = 10
6 × 2 = 12
7 × 2 = 14
8 × 2 = 16
9 × 2 = 18
10 × 2 = 20
11 × 2 = 22
12 × 2 = 24

0 × 3 = 0
1 × 3 = 3
2 × 3 = 6
3 × 3 = 9
4 × 3 = 12
5 × 3 = 15
6 × 3 = 18
7 × 3 = 21
8 × 3 = 24
9 × 3 = 27
10 × 3 = 30
11 × 3 = 33
12 × 3 = 36

0 × 4 = 0
1 × 4 = 4
2 × 4 = 8
3 × 4 = 12
4 × 4 = 16
5 × 4 = 20
6 × 4 = 24
7 × 4 = 28
8 × 4 = 32
9 × 4 = 36
10 × 4 = 40
11 × 4 = 44
12 × 4 = 48

0 × 5 = 0
1 × 5 = 5
2 × 5 = 10
3 × 5 = 15
4 × 5 = 20
5 × 5 = 25
6 × 5 = 30
7 × 5 = 35
8 × 5 = 40
9 × 5 = 45
10 × 5 = 50
11 × 5 = 55
12 × 5 = 60

0 × 6 = 0
1 × 6 = 6
2 × 6 = 12
3 × 6 = 18
4 × 6 = 24
5 × 6 = 30
6 × 6 = 36
7 × 6 = 42
8 × 6 = 48
9 × 6 = 54
10 × 6 = 60
11 × 6 = 66
12 × 6 = 72

0 × 7 = 0
1 × 7 = 7
2 × 7 = 14
3 × 7 = 21
4 × 7 = 28
5 × 7 = 35
6 × 7 = 42
7 × 7 = 49
8 × 7 = 56
9 × 7 = 63
10 × 7 = 70
11 × 7 = 77
12 × 7 = 84

0 × 8 = 0
1 × 8 = 8
2 × 8 = 16
3 × 8 = 24
4 × 8 = 32
5 × 8 = 40
6 × 8 = 48
7 × 8 = 56
8 × 8 = 64
9 × 8 = 72
10 × 8 = 80
11 × 8 = 88
12 × 8 = 96

0 × 9 = 0
1 × 9 = 9
2 × 9 = 18
3 × 9 = 27
4 × 9 = 36
5 × 9 = 45
6 × 9 = 54
7 × 9 = 63
8 × 9 = 72
9 × 9 = 81
10 × 9 = 90
11 × 9 = 99
12 × 9 = 108

0 × 10 = 0
1 × 10 = 10
2 × 10 = 20
3 × 10 = 30
4 × 10 = 40
5 × 10 = 50
6 × 10 = 60
7 × 10 = 70
8 × 10 = 80
9 × 10 = 90
10 × 10 = 100
11 × 10 = 110
12 × 10 = 120

0 × 11 = 0
1 × 11 = 11
2 × 11 = 22
3 × 11 = 33
4 × 11 = 44
5 × 11 = 55
6 × 11 = 66
7 × 11 = 77
8 × 11 = 88
9 × 11 = 99
10 × 11 = 110
11 × 11 = 121
12 × 11 = 132

0 × 12 = 0
1 × 12 = 12
2 × 12 = 24
3 × 12 = 36
4 × 12 = 48
5 × 12 = 60
6 × 12 = 72
7 × 12 = 84
8 × 12 = 96
9 × 12 = 108
10 × 12 = 120
11 × 12 = 132
12 × 12 = 144

This form of writing the multiplication table in columns with complete number sentences is still used in some countries, such as Bosnia and Herzegovina,[ citation needed ] instead of the modern grids above.

Patterns in the tables

There is a pattern in the multiplication table that can help people to memorize the table more easily. It uses the figures below:

 
12324
456
78968
05 0 
Figure 1: OddFigure 2: Even
Cycles of the unit digit of multiples of integers ending in 1, 3, 7 and 9 (upper row), and 2, 4, 6 and 8 (lower row) on a telephone keypad Multiplication mnemonic.svg
Cycles of the unit digit of multiples of integers ending in 1, 3, 7 and 9 (upper row), and 2, 4, 6 and 8 (lower row) on a telephone keypad

Figure 1 is used for multiples of 1, 3, 7, and 9. Figure 2 is used for the multiples of 2, 4, 6, and 8. These patterns can be used to memorize the multiples of any number from 0 to 10, except 5. As you would start on the number you are multiplying, when you multiply by 0, you stay on 0 (0 is external and so the arrows have no effect on 0, otherwise 0 is used as a link to create a perpetual cycle). The pattern also works with multiples of 10, by starting at 1 and simply adding 0, giving you 10, then just apply every number in the pattern to the "tens" unit as you would normally do as usual to the "ones" unit.

For example, to recall all the multiples of 7:

  1. Look at the 7 in the first picture and follow the arrow.
  2. The next number in the direction of the arrow is 4. So think of the next number after 7 that ends with 4, which is 14.
  3. The next number in the direction of the arrow is 1. So think of the next number after 14 that ends with 1, which is 21.
  4. After coming to the top of this column, start with the bottom of the next column, and travel in the same direction. The number is 8. So think of the next number after 21 that ends with 8, which is 28.
  5. Proceed in the same way until the last number, 3, corresponding to 63.
  6. Next, use the 0 at the bottom. It corresponds to 70.
  7. Then, start again with the 7. This time it will correspond to 77.
  8. Continue like this.

In abstract algebra

Tables can also define binary operations on groups, fields, rings, and other algebraic systems. In such contexts they are called Cayley tables.

For every natural number n, addition and multiplication in Zn, the ring of integers modulo n, is described by an n by n table. (See Modular arithmetic.) For example, the tables for Z5 are:

For other examples, see group.

Hypercomplex numbers

Hypercomplex number multiplication tables show the non-commutative results of multiplying two hypercomplex imaginary units. The simplest example is that of the quaternion multiplication table.

Quaternion multiplication table
×1ijk
11ijk
ii−1kj
jjk−1i
kkji−1

For further examples, see Octonion § Multiplication, Sedenion § Multiplication, and Trigintaduonion § Multiplication.

Chinese and Japanese multiplication tables

Mokkan discovered at Heijō Palace suggest that the multiplication table may have been introduced to Japan through Chinese mathematical treatises such as the Sunzi Suanjing, because their expression of the multiplication table share the character in products less than ten. [8] Chinese and Japanese share a similar system of eighty-one short, easily memorable sentences taught to students to help them learn the multiplication table up to 9 × 9. In current usage, the sentences that express products less than ten include an additional particle in both languages. In the case of modern Chinese, this is (); and in Japanese, this is (ga). This is useful for those who practice calculation with a suanpan or a soroban, because the sentences remind them to shift one column to the right when inputting a product that does not begin with a tens digit. In particular, the Japanese multiplication table uses non-standard pronunciations for numbers in some specific instances (such as the replacement of san roku with saburoku).

The Japanese multiplication table
×1 ichi2 ni3 san4 shi5 go6 roku7 shichi8 ha9 ku
1 inin'ichi ga ichiinni ga niinsan ga saninshi ga shiingo ga goinroku ga rokuinshichi ga shichiinhachi ga hachiinku ga ku
2 nini ichi ga nini nin ga shini san ga rokuni shi ga hachini go jūni roku jūnini shichi jūshini hachi jūrokuni ku jūhachi
3 sansan ichi ga sansan ni ga rokusazan ga kusan shi jūnisan go jūgosaburoku jūhachisan shichi nijūichisanpa nijūshisan ku nijūshichi
4 shishi ichi ga shishi ni ga hachishi san jūnishi shi jūrokushi go nijūshi roku nijūshishi shichi nijūhachishi ha sanjūnishi ku sanjūroku
5 gogo ichi ga gogo ni jūgo san jūgogo shi nijūgo go nijūgogo roku sanjūgo shichi sanjūgogo ha shijūgokku shijūgo
6 rokuroku ichi ga rokuroku ni jūniroku san jūhachiroku shi nijūshiroku go sanjūroku roku sanjūrokuroku shichi shijūniroku ha shijūhachirokku gojūshi
7 shichishichi ichi ga shichishichi ni jūshishichi san nijūichishichi shi nijūhachishichi go sanjūgoshichi roku shijūnishichi shichi shijūkushichi ha gojūrokushichi ku rokujūsan
8 hachihachi ichi ga hachihachi ni jūrokuhachi san nijūshihachi shi sanjūnihachi go shijūhachi roku shijūhachihachi shichi gojūrokuhappa rokujūshihakku shichijūni
9 kuku ichi ga kuku ni jūhachiku san nijūshichiku shi sanjūrokuku go shijūgoku roku gojūshiku shichi rokujūsanku ha shichijūniku ku hachijūichi

Warring States decimal multiplication bamboo slips

A bundle of 21 bamboo slips dated 305 BC in the Warring States period in the Tsinghua Bamboo Slips (清華簡) collection is the world's earliest known example of a decimal multiplication table. [9]

Qinghuajian Suan Biao example.svg
A modern representation of the Warring States decimal multiplication table used to calculate 12 × 34.5

Standards-based mathematics reform in the US

In 1989, the National Council of Teachers of Mathematics (NCTM) developed new standards which were based on the belief that all students should learn higher-order thinking skills, which recommended reduced emphasis on the teaching of traditional methods that relied on rote memorization, such as multiplication tables. Widely adopted texts such as Investigations in Numbers, Data, and Space (widely known as TERC after its producer, Technical Education Research Centers) omitted aids such as multiplication tables in early editions. NCTM made it clear in their 2006 Focal Points that basic mathematics facts must be learned, though there is no consensus on whether rote memorization is the best method. In recent years, a number of nontraditional methods have been devised to help children learn multiplication facts, including video-game style apps and books that aim to teach times tables through character-based stories.

See also

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References

  1. Trivett, John (1980), "The Multiplication Table: To Be Memorized or Mastered!", For the Learning of Mathematics, 1 (1): 21–25, JSTOR   40247697 .
  2. 1 2 3 Qiu, Jane (January 7, 2014). "Ancient times table hidden in Chinese bamboo strips". Nature News. doi: 10.1038/nature.2014.14482 . S2CID   130132289.
  3. Wikisource:Page:Popular Science Monthly Volume 26.djvu/467
  4. for example in An Elementary Treatise on Arithmetic by John Farrar
  5. David E. Smith (1958), History of Mathematics, Volume I: General Survey of the History of Elementary Mathematics. New York: Dover Publications (a reprint of the 1951 publication), ISBN   0-486-20429-4, pp. 58, 129.
  6. David W. Maher and John F. Makowski. "Literary evidence for Roman arithmetic with fractions". Classical Philology, 96/4 (October 2001), p. 383.
  7. Leslie, John (1820). The Philosophy of Arithmetic; Exhibiting a Progressive View of the Theory and Practice of Calculation, with Tables for the Multiplication of Numbers as Far as One Thousand. Edinburgh: Abernethy & Walker.
  8. "「九九」は中国伝来...平城宮跡から木簡出土". Yomiuri Shimbun. December 4, 2010. Archived from the original on December 7, 2010.
  9. Nature article The 2,300-year-old matrix is the world's oldest decimal multiplication table