Unit 1 Multiplication 1. learning point

1, three digits times two digits, and the product is either four digits or five digits.

2. Calculation rules for multiplying three digits by two digits: first multiply the digits of two digits with each digit of three digits, and the product is aligned with the digits; Then multiply the number of two digits with each of the three digits, and the product is aligned with the ten digits; Finally, add the product twice.

3. Multiplication calculation method ending in 0: Now multiply the non-zero parts of the two multipliers, and then see how many zeros are at the end of the two multipliers, and add several zeros at the end of the product. Second, the typical analysis of 1

Xinhua Bookstore donated books to Wenchuan Hope Primary School 12 class, with an average of 46 books per class/KLOC-0. How many books did Xinhua Bookstore donate? Analysis method 1

How many books are donated to Xinhua Bookstore through the examination of the topic? That is, what is 12 146, so examples are 146× 12 or 12× 146. In the vertical calculation, multiply 2 by 12 and 146. Method 2

In the above analysis, another example method is mentioned, namely 12× 146. In vertical calculation, 6 on 146 bit is multiplied by 12, which is equal to 72, and 2 on the last bit of 72 should be aligned with 1 bit; Multiply the tenth bit of 146 and 12 by 4, which is equal to 48, and the 8 at the end of 48 should be aligned with the tenth bit; Then multiply 1 and 12 by the hundred of 146, which is equal to the last 2 of 12 and 12 should be aligned with the hundred; Finally add the product of three times. practise

1, vertical calculation

17× 243 = 308× 65 =175× 24 = 203×19 = 2, a three-digit number times a two-digit number, the product may be () digits, or the product of () digits 28×79 may be () digits. The product of 124×65 is () digits. 3. Application questions

(1), the school bought 85 sets of single tables and chairs, each table 140 yuan, each chair 65 yuan. How much did it cost?

(2) The store bought 845 schoolbags and sold 537. (1) The unit price of schoolbags sold is 85 yuan. How much does * * * earn? (2) How much can I earn by selling the remaining schoolbags in 65 yuan at the unit price? Typical case analysis II

Example calculation 470×20

First, align 47 and 2 before 0. Multiply 47 by 2 to get 9400, so add two zeros after 94.

There are two zeros at the end of the two multipliers. Don't forget to add two zeros at the end of the product after multiplication. practise

1, vertical calculation

450× 60 = 800× 90 = 430×14 = 30× 205 = 2. Judgment

1, two multipliers have three zeros at the end, and the product of these two multipliers has at least three zeros at the end. ( )

2. When two digits are multiplied by three digits, there must be 0 in the middle of a multiplier and 0 in the middle of the product. () There are two zeros at the end of 3.750×40. ( )。 4、 180×40= 1800×4 ( )

Unit 2 liters and milliliters 1. learning point

1, 1 l (L)= 1000 mL (ml, ml)

2. A cubic container whose length, width and height are 1 decimeter from the inside out is exactly 1 liter. 1 litre water weight 1 kg. A glass of water in life is about 250ml；; A pressure cooker can hold about 6 liters of water; A domestic pool can hold about 30 liters of water and a washbasin can hold about 10 liters of water. A bathtub has about 400 liters of water; The capacity of a thermos bottle is about 2 liters, a goldfish bowl is about 30 liters, a bottle of drinks is about 400 ml, a pot of water is about 5 liters, and a spoonful of water has 10 ml.

The total blood volume of a healthy adult is about 4000-5000 ml. Voluntary blood donors generally donate 200 ml of blood each time.

4. 1 ml is approximately equal to 20 drops of water. Second, the typical analysis of 1

Example: Pour 1 liter of water into a measuring cup, each cup is 500 ml. How many cups can you pour? How many milliliters is 1 liter? Analysis From the actual operation, we can see that 1 bottle 1 liter of water is poured into a 500 ml measuring cup, and two cups are just filled, so we can know that 1 liter is equal to two 500 ml. Exercise 1, fill in the blanks

4 l =()ml 2000ml =()l 9 l =()ml 5000ml =()l 50000ml =()l 12 l =()ml 2。 Play ">", "

800 ml ○ 1 liter 7 liters ○7000 ml 2500 ml 03 liters 3. The capacity of the following container is 1 liter. Please draw a picture to indicate 1/2 liters and 1/4 liters.

Typical case analysis II

Example: an infusion bottle 250 (), a bottle of beverage 750 (), a basin of water 16 ().

For smaller containers, milliliters are used as the unit of capacity, while for larger containers, liters are used as the unit of capacity.

The unit to be filled is, you can first contact what is 1 liter and 1 ml, and then estimate the size of the container according to your own experience to see if it is reasonable to fill it yourself. practise

1, fill in the appropriate company name.

A bottle of ink is about 60 (). A large bottle of glucose solution is about 500 (). A glass of water in life is about 250 (). A domestic pool contains about 30 (), and a washbasin contains about 10 (). The capacity of a thermos bottle is about 2 (), a goldfish bowl is about 30 (), a bottle of beverage is about 400 (), and the total blood of a healthy adult is about 4 ().

1, a bottle of Wahaha has 180 liters. ? Ming Ming drank 400 ml of milk today. () 3. The capacity of the water bottle is larger than that of the milk bottle. ? () 4. 1 litre water weight 1 kg. ( )

5. The amount of blood donated by unpaid blood donors is generally 200ml each time. ( )