Calculation:
1, oral estimation:
900÷30 12×40 480÷80 16×6 12×7
420÷60 100×26 2400+300 5600÷70 320+780
90÷ 18 16×25 480+30 300-25×4 100-72÷8
689×5≈ 5430÷9≈ 3976÷8≈ 2080×4≈ 260×8≈
2, vertical calculation and checking calculation:
209×43 8652÷36
3. Off-mold calculation:
2 10+405÷9× 12 4020÷20- 18× 1 1
4, column calculation:
What's the difference between 345 minus 345 and 5? What is the sum of the quotients of 882 divided by 2 1 and 18?
Basic knowledge:
I. Fill in the blanks:
1, given the time and work efficiency, the relationship between the total work is: ().
2. The sum of the largest two digits and the smallest two digits is (), and the difference is ().
3. In □24÷35, if the quotient is two digits, the minimum value in □ should be filled in ().
4. Fill in the appropriate numbers:
12m = () decimeter 9 tons = () kg 1800 square decimeter = () square meter.
5, the dividend is expanded by 2 times, the divisor is unchanged, and the quotient ().
6. The rectangle is 60 meters long, 50 meters wide and has a circumference of ().
7. When a two-digit number is divided by three digits, the quotient is two digits, which means that the first two digits of the dividend are greater than the divisor ().
8. Fill in the appropriate unit name:
A pencil is 18 (), a desk is 7 () and a big tree is 15 ().
The length of the classroom is 9 () 90m = () decimeter = () cm.
9. The multiple of a number 19 is 36 1, and this number is ().
10,9275 Write the mantissa after omitting the highest digit ().
1 1. The rectangle has an area of 42 square decimeters, a width of 6 decimeters and a length of () decimeters.
12. To request the speed of a car, you must know two conditions () and (), and their relationship is ().
13 and () What can I fill in?
14×( )