Odd numbers are suitable for running out.

Odd numbers are suitable for exhaustion, which is related to the traditional cultural significance.

The ancients thought that odd numbers in numbers were positive numbers, which were auspicious days of the zodiac and suitable for going out.

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. Odds can be divided into positive odd numbers and negative odd numbers. As for the nature of odd numbers, there must be an odd number and an even number in two consecutive integers; Odd number+odd number = even number; Even+odd = odd; Even number+even number+...+even number = even number; Odd number-odd number = even number; Parity = odd number; Odd-even = odd; If a and b are integers, the parity of a+b and a-b is the same, that is, a+b and a-b are both odd or even; The product of n odd numbers is odd, and the product of n even numbers is even; If one of the formulas is even, the product is even; Odd numbers are 1, 3, 5, 7, 9; Even numbers are 0, 2, 4, 6, 8; The square of an odd number divided by 2, 4 and 8 is1; The square difference between any two odd numbers is a multiple of 2, 4 and 8; When an odd number is divided by 2, the remainder is 3.