Numbers with units of 1, 3, 5, 7 and 9 are singular, also called odd numbers; Numbers with units of 2, 4, 6, 8 and 0 are called even numbers. All integers are either odd or even. If a number is a multiple of 2, it is even.

Odd number is another name for positive odd number in mathematics.

Even number is another name for positive even number in mathematics.

Extended data:

Regarding odd and even numbers, there are the following properties:

(1) Two consecutive integers must have an odd number and an even number;

(2) Odd number+odd number = even number; Even+odd = odd; Even number+even number+...+even number = even number;

(3) Odd-odd = even; Parity = odd number; Odd-even = odd;

(4) 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;

(5) 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;

(6) Odd numbers are 1, 3, 5, 7 and 9; Even numbers are 0, 2, 4, 6, 8;

(7) Divide the square of odd numbers by 2, 4 and 8, and the remainder is1;

(8) The square difference of any two odd numbers is a multiple of 2, 4 and 8.

(9) The remainder of an odd number divided by 2 is 1.