Key points of the second volume of mathematics in senior one.

Updated the main points of the first grade mathematics (Volume II), corrected some small mistakes, and the topic did not provide answers. Parents need to supervise their children to do it in order to achieve the effect of learning.

Unit 1 Understanding Graphics

1, understanding and drawing

2. Tangram consists of 1 square, 1 parallelogram and 5 triangles.

3, the method of missing a few bricks

(1) Just draw a picture according to the arrangement of bricks.

(2) Don't start work or write. Looking at the first floor, you can see that some bricks are missing on the third and fifth floors. Look at the second floor and you will know that there are some bricks missing on the fourth and sixth floors.

(3) Count how many bricks there are on one floor, and each floor is the same length, and work out how many bricks are missing on each floor.

Missing (? 8) block

Fold along the dotted line and it becomes a cube.

Where 1 and (? ) face to face.

Method: somewhere in between.

① to ③, ② to ⑤, ④ to ⑤.

Subtraction of abdication in the second unit 20

1, calculation method

1 1-9=□

Method 1: break the ten methods

1 1-9=2

First: 10-9= 1, then: 1+ 1=2.

Method 2: Want to add and subtract.

1 1-9=2

Because: 9+2= 1 1, so: 1 1-9=2.

Method 3: continuous subtraction

1 1-9=2

1 1- 1- 1- 1- 1- 1- 1- 1- 1- 1=2

Step 2 solve the problem

(1) Select valid information and exclude interference information.

Solving a problem requires two conditions and one problem.

Example: Xiaoming has 14 chickens and 5 ducks. There are six cocks and how many hens?

Analysis: The two conditions are 14 chickens and 6 cocks.

The question is how many hens are there?

Interference message: 5 ducks.

14-6=8 (only)

Answer: There are 8 hens.

(2) How much is one number more than another, or how much is one number less than another? (subtraction)

Example 1: Xiaohua has 12 apples, Xiaofang has 7 apples, and Xiaohua has more apples than Xiaofang.

12-7=5 (pieces)

Answer: Xiaohua has five more than Xiao Fang.

Example 2: Xiaohua has 12 apples, and Xiaofang has 7 apples. How many apples are there in Xiaofang than Xiaohua?

12-7=5 (pieces)

Answer: Xiao Fang is five years younger than Xiaohua.

Unit 3 Classification and Arrangement

(Requirements: I can fill in forms, draw forms, give classification standards, and classify myself. )

The standards of classification are consistent, and the results of classification are consistent.

Different classification standards will lead to different classification results.

1, for adults and children

2. By gender

Tell me what information you know.

4. What math questions would you ask? And answer.

Unit 4 Understanding of Numbers within 100

1、45、46、47、( ? )、( ? )、( ? )、( ? )、( ? )

10、20、30、( ? )、( ? )、( ? )、( ? )、( ? )

Thirty-five is followed by five (), (), (), (), (), (), ().

2, 10 one (? ), 10 ten (? ); I am made up of eight ones and three tens (? ), I am composed of five tens and eight ones (? ); I'm 79, and the front is (? ), followed by (? ); I'm 85, three years younger than me is (? )。

3, fifty-two write (), thirty-seven write (? ); 89 Pronunciation ()

68 is pronounced as (), and reading and writing all start from the high position.

Starting from the right, the first one is (), the second one is (), and the third one is ().

Step 4 compare sizes

(1) Compare ten digits first, and the number with ten digits is larger.

For example: 34 058

(2) Ten digits are the same, and then compare one digit, and the one with the largest digit is the largest.

62○69

5. Learn to describe the relationship between two numbers in the language of more, less, more and less.

For example, 18 is greater than 16 and 16 is less than18;

99 is much more than 10, and 10 is much less than 99.

6. Integer decimal plus one digit and corresponding subtraction.

Adding dozens means adding several ones, and the result is dozens.

For example: 30+2=32

Method: What is the composition of (1) number? Thirty plus two equals thirty-two

(2) the relationship between addition and subtraction.

30+2=32 2+30=32

32-30=2 32-2=30

(3) Continue to count or count backwards. 30+2=32

Next counting method: 3 1, 32

32-2=30

Countdown method: 3 1, 30

7. The largest number is (? ),

The largest two digits (? ),

The smallest two digits (? )。

Unit 5 Understanding RMB

1, fill in.

1 yuan = 10 angle.

1 angle = 10 point

1 yuan = 100 integral.

5 jiao = (? ) points

6 yuan = (? ) angle

20 points = (? ) angle

3 yuan 9 Angle = (? ) angle

1angle 2 points = (? ) points

13 Angle = (? ) yuan (? ) angle

26 points = (? ) angle (? ) points

4 yuan +8 yuan = (? ) yuan

5 jiao+1 yuan 3 jiao = (? ) yuan (? ) angle

4 angle+9 angle = (? ) Angle = (? ) yuan (? ) angle

2. compare it.

5 cents (? ) 5 yuan

3 yuan (? ) 2 yuan 9 jiao

89 jiao (? ) 8 yuan 9 jiao

5 yuan 6 jiao (? ) 6 yuan 5 jiao

3.4 cents (? ) 3 yuan 4 jiao

3 yuan 6.8 (? ) 3 yuan scored 6.4.

Compare elements first, then compare angles, and finally compare points.

Step 3 change it

1 5 yuan can be exchanged (? ) Zhang 1 yuan,

1 block 10 yuan can be exchanged (? ) Zhang 1 yuan;

1 block 10 yuan can be exchanged (? ) Zhang 5 yuan,

1 block 10 yuan can be exchanged (? ) Zhang 2 yuan;

1 20 yuan can be exchanged (? ) 10 yuan,

1 50 yuan can be exchanged (? ) 10 yuan;

1 block 100 yuan can be exchanged (? ) 10 yuan,

1 block 100 yuan can be exchanged (? ) Zhang 50 yuan;

1 1 yuan can be exchanged (? ) Zhang 1 angle or change it to (? ) Zhang 5 jiao;

1 5 yuan can be exchanged (? ) Zhang 1 yuan and (? ) Zhang 2 yuan;

1 block 100 yuan can be exchanged (? ) Zhang 50 yuan and (? ) 10 yuan;

4、

(1)1What two kinds of toys can I buy in 9 yuan?

(2) How much does it cost to buy dolls and balls?

Unit 6 Addition and subtraction within 100

1, positive and negative integer ten digits

2+3=5 ? Representation: 2 plus 3 1 equals 5 1, which is 5.

20+30=50 ? Instruction: two tens plus three tens equals five tens, which is 50.

70-30=40 ? Seven tens MINUS three tens equals four tens, which is forty.

Add and subtract ten integers, just add and subtract the tenth digit.

2, two digits plus one digit, integer ten.

(1) Do not carry it.

25+2=27 25+20=45

Count first: 5+2=7. Count first: 20+20=40.

Recalculate: 20+7=27? Recalculation: 40+5=45

When you add two digits to one digit and integer ten digits, you should pay attention to the addition of two digits and the addition of two digits and ten digits.

The high bits of the same number can be added directly.

(2) carry

24+9=33 ? 24+9=33

Calculate first: 4+9= 13 Calculate first: 24+6=30.

Recalculate: 20+ 13=33? Recalculation: 30+3=33

★ Two digits plus one digit: the sum of digits is less than ten, and the ten digits remain unchanged;

When the numbers add up to ten, you must enter 1 to ten digits.

3, two digits MINUS one, integer ten.

(1) Don't give up

35-2=33 35-20= 15

Calculate first: 5-2=3. Let's calculate first: 30-20= 10.

Recalculate: 30+3=33? Recalculation: 10+5= 15.

When you subtract one digit from two digits, you should pay attention to the subtraction of one digit and one digit, and the subtraction of ten digits and ten digits.

The high bits of the same number can be directly subtracted.

(2) abdication

36-8=28 ? 36-8=28

Calculate first: 10-8=2 calculate first: 16-8=8.

Recalculate: 26+2=28 Recalculate: 20+8=28.

★ Two digits minus one digit: minus one digit is enough, and the number on the tenth digit remains unchanged, which is a subtraction without abdication.

If the number of digits is not enough, 1 (make ten) from ten digits is abdication subtraction.

4, brackets

10-2-3=5 10-(2+3)=5

Calculate first: 10-2=8 Calculate first: 2+3=5.

Recalculate: 8-3=5? Recalculation: 10-5=5

What's in brackets counts first.

5. Solve the problem of continuous addition

Three students stacked the little stars together, each with six. How many little stars did they fold together?

(1) Add solution

6+6+6= 18 (pieces)

(2) List the solutions

6. Solve the problem of continuous decline