The natural numbers we know now are divided into odd numbers and even numbers, that is, odd numbers and even numbers learned in senior one. Because senior one students can't understand the concepts and meanings of odd and even numbers, they first introduce natural numbers in the form of odd and even numbers.

Singular numbers are numbers that are not divisible by 2 (that is, numbers that are still 1 after being divisible by 2), such as 1, 3, 5, 7, 9,1,while even numbers are numbers that are divisible by 2 (a number is still 0 after being divisible by 2).

The understanding of odd and even numbers is the first and very important step in learning mathematics. Usually at home, children must know more about numbers, teach more and learn more games and books related to numbers.