The opposite sides of a rectangle are equal, and the four sides of a square are equal.

3. A square can be divided into two triangles or two rectangles when it is folded in half.

4. Two identical rectangles can be spelled into squares or rectangles.

Four identical small squares can form a big square. Eight identical cubes can make up a big cube.

6. Brick repair problem

Method 1: Mark the numbers layer by layer, and then underline the odd and even numbers.

Method 2: first find a layer that doesn't need to be mended, count how many bricks there are, and then have a look. Every floor is missing a few bricks, so add one.

7. 10 is 10, 1 0 is also 10.

8. In the numerical table, from the right, the first digit is (), which means several (); The second place is (), which means several (); The third place is (), which means several (). Reading and writing numbers all start from high places.

9. The smallest number is 0, the smallest number is 1, the largest number is 9, the smallest two digits are 10, the largest two digits are 99 and the smallest three digits are 100.

10, with five tens, we write 5 in the tenth place, with five ones, and we write 5 in the unit, so the number represented by five ones and five tens is (), which is pronounced as (), and the meaning of 5 in the unit is different from that of 5 in the tenth place.

1 1. Arrange the following numbers in descending order: 23, 59, 78, 73, 54, 36.

() It's relatively large. Please see clearly how the topic is arranged, and write one across and one without missing.

12, a little more is a little more. More means more. Can you say the same thing?

13, draw six points on ten and one, which number ()

Draw nine dots on tens and digits, which two digits ()

14, 1 yuan = 10 angle 1 angle = 10 minute/0 yuan = 1 00 minute 1 hour =60 minutes and a half.

15. Time units are: hours, minutes and seconds. The units of RMB are: yuan, jiao and fen.

16, 1 yuan 5 angle +9 angle = () yuan () angle unit is the same, angle and angle are added, and the full angle 10 is changed to 1 yuan.

5: 20, 50 minutes later = (), () The unit at the back is minutes, so the minutes and phases are added, 20+50=70, 70 is greater than 60, so 5: 00 becomes 6: 00, 70-60= 10.

17, if the ratio is greater than the ratio is less than, subtraction must be done. To find a * * * number, we need to add, find the remainder and subtract.

18, short and thick is the hour hand, long and thin is the minute hand, the minute hand points to 12, and the hour hand points to several hours. When the hour hand goes by, we have to look at the numbers inside, and when the minute hand goes by, we have to look at the numbers outside. When doing this, if the minute hand is between two numbers, we must delay the minute hand.

19, there are 12 squares and 60 squares on the clock face. The minute hand goes 1 grid, which means 1 minute, and goes 1 grid, which means 5 points. Clockwise 1 grid, indicating 65438+.

20. Writing the number 5 before 63 () means it is smaller.

Write the number 5 after 78 () to indicate that it is greater than it.

2 1. Xiaoming bought a pencil, paid 50 yuan and got 5 yuan back. How much is this pencil box? Column type:

Method: We need to get it back, because we paid too much money, so we have to do subtraction.

22, queuing problem:

Method 1: Please draw with a circle.

Method 2: Look at the first word. (1) has no initial. Add two numbers, and then+1:A+B+ 1.

(2) There is only one prefix, and directly add two numbers: A+B..

(3) There are two prefixes. After adding the two numbers,-1:A+B- 1.

Example 1: There are 8 people on my left and 9 people on my right. How many people are there?

Draw a picture: OK:

Example 2: Counting from left to right, I rank fifth, and there are eight people on my right. How many people are there?

Draw a picture: OK:

Ex. 3: I rank seventh from the bottom and third from the bottom. How many people are there?

Draw a picture: OK:

23. Put a square with at least 4 sticks; Put a triangle with at least three sticks; It takes at least six sticks to make a rectangle.

24. When the hour hand and the minute hand coincide, it is 12, and when they form a straight line, it is 6 o'clock.

25. One 20 yuan can be exchanged for four 5 yuan and two 10 or 10 2 yuan.

One 100 yuan can be changed into 1 50 yuan and five 10 yuan. Please turn to page 49, read it carefully and take notes.

5 yuan can exchange 1 2 yuan and 3 1 yuan 5 yuan for 2 2 yuan and 1 1 yuan.