Singular number is another name for positive odd number in mathematics. Mathematically, as opposed to even numbers (positive even numbers), it can be expressed as 2n+ 1 (n is an integer greater than or equal to 0).

1. As opposed to even numbers, it can be expressed as 2n+ 1 (Arabic numerals).

Contrary to the plural, in some languages, it refers to a single quantity represented by the word itself. For example, in English, countable nouns have both singular and plural forms, indicating that a person or thing is singular and more than one person or thing is plural.

1 and even number are nicknames for even numbers in mathematics. In mathematics, it can be expressed as 2n (n is a positive integer) as opposed to singular. Even numbers must be divisible by 2. It is worth noting that 0 is an even number (in 2002, the International Mathematical Association stipulated that 0 is an even number, and in 2004, China also stipulated that 0 is an even number).

2. Grammatical terms, which mostly appear in the process of language development, mean "two", "one pair" and "one pair". They are the same forms of words with singular and plural numbers (even the majority), such as ancient Greek, old English and old Russian. Now the concept of even numbers no longer exists, but only remains in some languages with a small range of use, such as Sanskrit, Hebrew, Arabic and so on. Some languages also have zero or three numbers, such as Sursurunga.