I'm not asking who is singular. I mean, what is singular? Understand the concept. Understand? The most important thing in mathematics learning is the concept.

? What is singular? Numbers that cannot be paired, that is, numbers that are not divisible by 2, are called singular numbers.

? A few, okay? A pair is a pair. How many pairs of socks are there?

Two. Two are just a pair. These two girls have a loud voice.

That's right. A number that cannot be divided into two parts is singular. For example, 1 means 1 instead of 1 right. 3 is 1 half, 5 is 2 and a half, 7 is 3 and a half, and 9 is 4 and a half. Can't be completely divided into whole pairs, so they are all singular.

Got it. What are odd numbers and even numbers?

What is an even number? A number that can be divided into pairs, that is, a number that is divisible by 2, is a double number. For example, 2 is 1, 4 is 2, 6 is 3, 8 is 4, and 10 is 5. In other words, 2 is 1 2, 4 is 2 2, 6 is 3 2, 8 is 4 2, and 10 is 5 2. You got it?

After knowing the concepts of singular and even, let's study the relationship between singular and even.

1.2.3 .4.5.6.7 .8.9

What can you find by observing their relationship?

Is odd plus 1 or odd minus 1 even?

Conversely, is even plus 1 or even minus 1 singular?

That 0 is 1 minus 1. 1 is singular, so 0 is even?

0 is an even number. For example, 10, 20, 30, all numbers are even.

After knowing these concepts, let's learn the fourth question of single and even numbers: the difference between single and even numbers: odd numbers have centers, and even numbers have no centers. Draw pictures, organize.

Finally, how to judge whether a number is singular or even?

Look at the unit of this number.

If the unit is 1, 3, 5, 7, 9, it is singular.

If the unit is 0, 2, 4, 6, 8, it is an even number.

For example, 266, the unit is 6, what is it? 1237, the unit is 7, what is it?