1, read the number within 20.

Positive numbers: 012345678 91012131415161.

Countdown: in descending order: 20 19 18 17.

Two 2-digit numbers: 02 46810141618 20 (positive numbers, reciprocal numbers or numbers starting from the specified middle number are required).

Five five-digit numbers: 05 10 15 20 (both positive and reciprocal).

Singular: 1, 3, 5, 7, 9

Even numbers: 2, 4, 6, 8, 10

(Note: 0 is neither singular nor even, and 0 is even. Odd and even numbers are said in life, and even numbers are said in mathematics. )

2. Two digits

(1) We often meet ten objects as a whole in our life. There is 10? One? Is it 1? 10? , one? Ten? Is it 10? One? .

For example, there are (1) tens and (1) ones in a:1; 1 1 has one (1 1). Two? 1? Have different meanings.

12 has (1) tens and (2) ones; 12 contains one (12).

14 has (1) tens and (4) ones; 14 contains one (14).

15 has (1) tens and (5) ones; 15 contains one (15).

19 has (1) tens and (9) ones; In other words, there is a (19) in 19.

There are (2) tens in 20; There are (20) in 20.

B: Look at the number board (1 1~20) and tell how many tens and one digits are on the board.

(2) On the counter, what is the first number from the right? What's the second place? (10) What does 1 bead mean? (stands for 1 one) What does the tenth 1 bead mean? (for 1 10)

(3) Read 1 1, 12, 13, 14, 15, 16, 17,/kloc.

For example: 14, read: 14 and write: 14. The unit digit is 4, which means 4 1, and the tenth digit is 1, which means 1 piece 10.

Grade One Mathematics "Comparing Size and Numbers"

For example, 1, queue the digital dolls: 5, 6, 10, 3, 20, 17, which can be arranged in descending order or descending order.

Pay attention to write a number when doing the problem, cross out one, don't be heavy, don't miss it. )

2, take any two numbers within 20, and you can use who is bigger than who or who is stronger than who.

For example, 16 is greater than 15, which means16 >; 15

9 is less than 13, indicating 9.

3、? Than? Usage of words

Do you see it? Than? Who's behind this? If it is greater than a few, add1to the number; If it is smaller, you have to subtract 1 from the number.

For example, the number 2 less than 5 is (3), and the number 3 greater than 4 is (7).

3. What number and what number?

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Look at the picture. How many numbers are there? (16 number) What's the number on the left? What's the number on the right? Circle the left three; Circle the second one on the right.

(When reviewing this kind of knowledge, we should distinguish between left and right and determine the direction at the same time; Know the difference between a few and a few. )

4. Adjacent numbers

2 is preceded by 1 and followed by 3. 2 plus 1 equals 3, 3 minus 1 equals 2. The numbers adjacent to 2 are 1 and 3.

3 is preceded by 2, and 3 is followed by 4. If you add 1 to 3, it is 4. If you divide 4 by 1, it is 3, and the numbers adjacent to 3 are 2 and 4.

20 is preceded by 19 and followed by 2 1, and the numbers adjacent to 20 are 19 and 2 1.