1 and the two meanings of multiplication;

(1) indicates: What is the sum of several?

(2) Indicate: What is the sum of several?

2. Three meanings of division:

(1) means: divide a number into several parts on average, and each part is several parts. (the meaning of sharing equally)

(2) indicates that there are several numbers in a number. (including the meaning of division)

(3) indicates that one number is several times that of another. (the meaning of multiple division)

Find out how many times one number is another number, and then divide it.

4. Know that one number is several times that of another number, and find a number by multiplication.

5. Know that one number is several times that of another number, and find another number by division.

6. Find the multiple of a number by multiplication.

7. Equitable formula: total number ÷ number of copies = number of copies.

8. Formula including division: total number ÷ each copy = number of copies.

9. Be familiar with the names of all parts of multiplication and division and the reading of formulas.

3 × 4 = 12

Multiplier Multiplier product (Pronunciation: 3 times 4 equals 12. )

12 ÷ 4 = 3

Divider divisor quotient (pronunciation: 12 divided by 4 equals 3. )

10, on the map, it is generally up north, down south, left west, right east.

1 1. If facing east, the back is west, the left is north, and the right is south.

If facing west, the back is east, the left is south and the right is north.

If you face south, your back is north, your left is east and your right is west.

12, 1 =60 minutes, 1 minute =60 seconds.

13, elapsed time = end time-start time

Start Time = End Time-Elapsed Time

End Time = Start Time+Elapsed Time

14, the common time unit is sometimes, minutes and seconds.

15. There are 12 big squares and 60 small squares on the clock. It takes 1 hour to walk a big square in an hour hand, 1 minute to walk a Little Square in a minute hand and 5 minutes to walk a big square in a minute hand.

16. In the division formula with remainder, the remainder must be less than the divisor.

17. According to the relationship between the parts of division, the following formula can be derived:

Dividend = Divider× Quotient+Remainder

Divider = (Divider-Remainder) ÷ Quotient

Quotient = (dividend-remainder) divider

Remainder = dividend divided by quotient

18, in the formula without brackets, there are addition and subtraction and multiplication and division. Calculate multiplication and division first, then add and subtract. If there is only addition and subtraction or only multiplication and division, it should be calculated from left to right. Formulas in brackets should be calculated first.

19. We usually refer to all directions as "East, West, South, North, Southeast, Northeast, Southwest and Northwest".

20, 10 One thousand is ten thousand; 10 One hundred is one thousand; 10 Ten is one hundred. 2 1. From the right, the first place is the unit, the second place is ten, the third place is one hundred, the fourth place is one thousand, and the fifth place is ten thousand.

22. Pay attention when reading: No matter how many zeros there are at the end, there are one or more zeros in the middle, and read only one zero. Note when writing numbers: there is nothing on any number, just fill in a zero placeholder on that number.