One, two, two, two, four.
One, three, two, three, six, three, three and nine.
Fourteen is four, two, four, eight, three, four, twelve, four, forty-six.
15 is 525, 135, 1525, 4525525.
16 is 62, 62, 38, 46, 24, 56, 36, 636.
Obtained .51989.99999998985
18 get 82 86 384 48312 584 68418 78516 8864.
1992 983927 4936 594 15 6954 796 13 8972 998 1
Extended data
Characteristics of formula
General 1 and 99 tables only use 9 numbers from 1 to 9.
2. Jiujiu table contains the commutativity of multiplication, so only 8972 is needed, and "9872" is not needed. 9 times 9 has 8 1 product, and the 99 table only needs 1+2+3+4+5+6+7+8+9 =45 product. In the Ming Dynasty, abacus also had 99 tables with 8 1 product. The 99 table of 45 items is called small 99, and the 99 table of 8 1 item is called big 99.
3. The shortest multiplication table in the ancient world. Maya multiplication table must have 190, Babylon multiplication table must have 1770, and Egypt, Greece, Rome, India and other countries must have infinite multiplication tables; Only 45/8 1 item is needed for the 99 table.
4. There is rhythm when reading aloud, which is convenient for memorizing the whole table.
Formulation development
China used the "99 formula" earlier. Sentences such as "3927", "684 18", "483 12" and "6636" can be found in books such as Xunzi, Guanzi, Huainanzi and Warring States Policy. It can be seen that as early as the Spring and Autumn Period and the Warring States Period, 99 multiplication songs became popular.
Jiujiubiao, also known as Jiujiuge and Jiuyinge, is the basic calculation rule in multiplication, division, square root and other operations in ancient China. It has been used for more than two thousand years. Pupils and some school-age children can recite it. But Europe didn't know this simple multiplication table until the beginning of 13 century.