Original meaning: natural numbers between 123 (one hundred and twenty-three), 122 and 124, and composite numbers of factorization (there are common divisors 1, 3,41,123). 123 stands for Do, Re and Mi in music.

Ten digits of the Indo-Arabic numeral system, arranged in numerical order. Numbers are written symbols used to represent numbers. Different numeration systems can use the same number. For example, the numbers "0" and "1" are used in both decimal and binary systems.

The same number has different representations in different counting systems. For example, the number 37 (Arabic numeral decimal) can be written in many ways: chinese numerals writes thirty-seven Roman numerals, and XXXVII Arabic numerals are written in binary 100 10 1.

Numbers are closely related to our lives. It not only has counting function, but also has rich philosophical connotation. Humans and numbers are closely connected from the beginning and will always be connected.

Numbers are called Arabic numerals, which has caused this historical misunderstanding. Later, with the wide spread in the world, everyone agreed with the term "Arabic numerals", which made people in many parts of the world mistakenly think that numerals were invented by Arabs. In fact, Arabs first began to use numbers widely.