An even number is a number in an integer that is divisible by 2, that is, a multiple of 2. Even numbers are also called even numbers. If a number is a multiple of 2, it is even and can be expressed as 2n. In decimal system, you can judge whether a number is odd or even by the number of digits: numbers with digits of 0, 2, 4, 6 and 8 are even, so even numbers within 1~ 10 are 2, 4, 6 and 8.
1 ~ 10, the odd numbers are 1, 3, 5, 7, 9.
Among integers, numbers that are not divisible by 2 are called odd numbers. In daily life, people usually call positive odd numbers singular, as opposed to even numbers. Odd numbers can be divided into positive and negative odd numbers. The mathematical expression of odd numbers is:
Positive odd numbers: 1, 3, 5, 7, 9,1,13, 15, 17, 19, 2/kloc-.
Negative odd numbers:-1, -3, -5, -7, -9,-1,-13,-15,-17,-/kloc.