Know the odd and even numbers in 1- 10: Play with chess pieces and children 1- 10, which is the number of 10.

Loneliness 1 person is singular;

When two good friends become a pair, they are not alone, that is, even numbers;

There is 1 block, no good friends, loneliness, which is singular;

There are two good friends, either lonely or even, and so on. Even number is another name for even number 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).