1, a number consists of 500 million, 39 million and 74 thousand. This number is written as (), and the mantissa after omitting ten thousand is about ().

Millions, written in hundreds of millions is ().

2. The smallest three digits divisible by multiples of 2 and 3 is ().

The prime factor of decomposition is ().

3. Cut the 5-meter-long rope into 6 sections on average, and each section accounts for () of the whole length.

Each segment is 10 meter long.

4. 1.08 tons = () tons () kg 3 days and 8 hours = () days.

8 cubic meters 16 cubic decimeter = () cubic meters

5. Given that A=2×2×3 and B=2×3×5, the greatest common divisor of A and B is () and the least common multiple is ().

6. Cylinders and cones are equal in height. If the volume of a cone is 18 cubic centimeter, then the volume of a cylinder is () cubic centimeter.

7. The scale of the map is 1:3000000. The measured distance between A and B is 4.5cm, and the actual distance is () km.

8. It takes 3 hours for Party A to drive the same distance, 4 hours for Party B, and the speed ratio between Party A and Party B is ().

9, in a certain period of time, the time spent on manufacturing a part is proportional to the number of such parts ().

10、0.75 =( )÷20 = 20:( ) =( )%

True or false: (tick right, x wrong) (10)1. There are 98 workers in a workshop, all of whom leave work in one day, and the attendance rate is 98% ().

2. Two composite numbers cannot be prime numbers. ( )

3. The quotient of a number divided by the true fraction must be greater than this number. ( )

4. If 3X=5Y, then x: y = 5: 3. ( )

5. Two triangles with the same area can definitely make a plane quadrilateral. ( )

Iii. Multiple choice questions: (fill in the serial number of the correct answer in brackets) (10)

1, 500g brine contains 50g salt, and the ratio of salt to water in brine is ().

⑴ 1:9 ⑵ 1: 10 ⑶ 1: 1 1

2,3: 2 and () can form a ratio.

⑴2:3 ⑵ 1.5 : 1 ⑶ 1: 1.5

3. The following () cannot be converted into a finite decimal.

⑴ ⑵ ⑶ ⑷

4. Make a cylindrical ventilation pipe with iron sheet, and how much iron sheet is needed for the ventilation pipe ().

(1) volume (2) volume (3) side area (4) surface area.

5. Given 3x+3= 12, 2x+ 1= ()

⑴ 7 ⑵ 14 ⑶ 9 ⑷ 8

Four, calculation questions: (24 points)

1. Numbers written directly: (4 points)

30- 19.02 = ÷2÷ =

1-0.49+0.06= ( + )×4=

2. Simple operation: (6 points)

25× 12.5×3.2 2.75×29- 1.75×29

4. Find the unknown X: (6 points)

X- 0.8X -6= 16 :X = :2