Multiplication table


In mathematics, a multiplication table is a mathematical table used to define a multiplication operation for an algebraic system.
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.

History

Pre-modern times

The oldest known multiplication tables were used by the Babylonians about 4000 years ago. However, they used a base of 60. 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.
The multiplication table is sometimes attributed to the ancient Greek mathematician Pythagoras. It is also called the Table of Pythagoras in many languages, sometimes in English. The Greco-Roman mathematician Nichomachus, 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.
In 493 AD, Victorius of Aquitaine wrote a 98-column multiplication table which gave 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."

Modern times

In his 1820 book The Philosophy of Arithmetic, mathematician John Leslie published a table of "quarter-squares" which could be used, with some additional steps, for multiplication up to 1000 × 1000. Leslie also recommended that young pupils memorize the multiplication table up to 50 × 50.
In 1897, August Leopold Crelle published Calculating tables giving the products of every two numbers from one to one thousand which is a simple multiplication table for products up to 1000 × 10000.
Tables showing all products of numbers from 1 to 10 or 1 to 12 are the sizes most commonly found in primary schools. The table below shows products up to 12 × 12:

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


The common multi-digit multiplication algorithms taught in school break that problem down into a sequence of single-digit multiplication and multi-digit addition problems. Single-digit multiplication can be summarized in a 100-entry table of all products of digits from 0 to 9. Because for any number, the rows and columns for multiplication by 0 are typically left out. Multiplication of integers is commutative,. Therefore, the table is symmetric across its main diagonal, and can be reduced to 45 entries by only showing entries where, as shown below. The table could be reduced further by leaving off rows and columns for multiplication by 1, the multiplicative identity, which satisfies.


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


This form of writing the multiplication table in columns with complete number sentences is still used in some countries, such as Colombia, Bosnia and Herzegovina, 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:


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. 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. For example, the tables for Z5 are:
+01234
001234
112340
223401
334012
440123

×01234
000000
101234
202413
303142
404321

For other examples, see group.

Hypercomplex numbers

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

Chinese and Japanese multiplication tables

The Chinese multiplication table consists of eighty-one terms. It was historically called the nine-nine table, because in ancient times it started with 9 × 9: nine nines beget eighty-one, eight nines beget seventy-two, etc. It was known in China as early as the Spring and Autumn period, and survived through the age of the abacus; pupils in elementary school today still must memorize it. A shorter version of the table consists of only forty-five sentences:
×1 一 yī2 二 èr3 三 sān4 四 sì5 五 wǔ6 六 liù7 七 qī8 八 bā9 九 jiǔ
1 一 yī一一得一
2 二 èr一二得二二二得四
3 三 sān一三得三二三得六三三得九
4 四 sì一四得四二四得八三四十二四四十六
5 五 wǔ一五得五二五一十三五十五四五二十五五二十五
6 六 liù一六得六二六十二三六十八四六二十四五六三十六六三十六
7 七 qī一七得七二七十四三七二十一四七二十八五七三十五六七四十二七七四十九
8 八 bā一八得八二八十六三八二十四四八三十二五八四十六八四十八七八五十六八八六十四
9 九 jiǔ一九得九二九十八三九二十七四九三十六五九四十五六九五十四七九六十三八九七十二九九八十一

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 如 in products less than ten. 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 得 ; and in Japanese, this is が. 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.
×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 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 roku ga kusan shi jūnisan go jūgo jūhachisan shichi nijūichi 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 shijū shijūgo
6 rokuroku ichi ga rokuroku ni jūniroku san jūhachiroku shi nijūshiroku go sanjūroku roku sanjūrokuroku shichi shijūniroku ha shijūhachi 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 gojūroku gojūshi 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 collection is the world's earliest known example of a decimal multiplication table.

Standards-based mathematics reform in the US

In 1989, the National Council of Teachers of Mathematics 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 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.
In 2024, the recommendation to learn the multiplication table was removed from the California Mathematics Curriculum Framework.