784070+78407. 1+7840.72+784.073+78.407=( )

2. Calculation:

=( )

3. Girls accounted for the total number of students who participated in various sports interest groups in a school last year. The students in the whole school are the same as last year. In order to welcome the 2008 Olympic Games, the number of students participating in various sports interest groups in the whole school increased by 20% this year, among which girls accounted for the total, so the number of girls participating in various sports interest groups increased by ()% compared with last year.

4. It is known that the difference of side length between two squares with different sizes is 12cm, and the difference of area is 984cm2, so the sum of their areas is () cm2.

5. When two natural numbers are divided, the quotient is 17 and the remainder is 13. The sum of known dividend, divisor, quotient and remainder is 2 1 13, and the dividend is ().

6. It is known that the sum of the ages of a football coach and two football players is 100 years old, and the age of the coach after 12 is the sum of the ages of two players, so the age of the coach this year is () years old.

7. There are more than 30 students in one class. In a math exam with a perfect score of 100, Xiaoming's score is an integer. If the ten digits of Xiao Ming's score are exchanged with the single digits, while the scores of other students in the class remain unchanged, and the average score of the whole class is just 2 points less than the original average score, then Xiao Ming got () in this exam.

8. There is a project that Party A needs 36 days to complete, Party B needs 30 days to complete and Party C needs 48 days to complete. Now Party A, Party B and Party C are doing it at the same time. During the working period, Party C has an integer number of rest days, while Party A and Party B have been working until the completion. It took an integer number of days to finish the project, so Party C had a rest of () days.

9. A parking lot has 44 three-wheeled agricultural vehicles, four-wheeled vans and six-wheeled trucks with 17 1 wheels. It is known that there are twice as few four-wheeled small Barbie six-wheeled trucks, so there are () three-wheeled agricultural vehicles in this parking lot.

10. A ship went down the river from Port A to Port B, and then immediately sailed back to Port A from Port B.. * * * It took eight hours to know that the river has traveled 20 kilometers per hour more than the current, and that the first four hours have traveled 60 kilometers more than the last four hours. Then, the distance between Port A and Port B is () kilometers.

1 1. The ratio of red balls to white balls in the bag is 19: 13. After putting some red balls, the ratio of red balls to white balls becomes 5: 3. After adding some white balls, the ratio of red balls to white balls becomes13:11; It is known that there are 80 fewer red balls than white balls, so there are () balls in the original bag.

12. In order to use electricity reasonably, a city encourages users to install "peak-valley" meters. The original electricity price in this city is 0.53 yuan per kWh. After the modification of the new electric meter, every night from 10 to 8: 00 the next morning is a "low valley", with a charge of 0.28 yuan per kilowatt hour, and the rest is a "peak hour" with a charge of 0.56 yuan per kilowatt hour, which is used to modify the new electric meter. The electricity consumption in two different time periods is 100 kWh, and users can save () yuan by refitting the meter 12 months.

1998 primary school mathematics Olympic examination paper

1. Given the equation × (19.98-□× )× (0.75+) = 0, the number represented by □ in the equation is ().

2. The following is a multiplication formula, and every □ is filled with a number, so the product in this formula should be ().

1□

× □□

□5□

□□□

□8□□

3. In the above picture, the side length of the big square is 10 cm. Connect the midpoints of the sides of the big square to get a small square, divide the sides of the small square into three parts, and then connect the bisector with the center and a vertex of the big square (as shown in the figure), so that the total area of the shaded part in the figure is equal to () square centimeters.

4. There are 24 four-digit numbers * * * consisting of 1, 2, 3 and 4, and there are no duplicate numbers. Arrange them from small to large, and the number of 18 is equal to ().

5. It is known that two numbers are coprime, their sum is divided by 5 and divided by 1, and their product is 2924, so their difference is ().

6. As shown in the figure, there are six points A, B, C, D, E and F on the boundary of square ACEF, where B and D are on the sides of AC and CE respectively, then the number of different triangles with three of these six points as vertices is ().

7. Among the natural numbers from 1 to 1998, the number of numbers divisible by 37 but not by 2 or 3 is equal to ().

8. The telephone number in Xiao Zhao is a five-digit number, which consists of five different numbers. Xiao Zhang said, "It's 8426 1." Xiao Wang said, "It's 26048." Xiao Li said, "It's 49280." Xiao Zhao said, "Who said that the number on a certain number is the same as the number on my phone number? Even if anyone guessed this number correctly, now each of you guessed these two numbers that are not adjacent to each other." This phone number is ().

9. The cost of a commodity per piece in 72 yuan was originally sold at a fixed price, and it can sell 100 pieces every day, and the profit of each piece is 25% of the cost. Later, it was sold at 90% of the fixed price, and the daily sales volume increased to 2.5 times. According to this calculation, the profit will increase by RMB () per day.

10. The speed ratio of the two trains A and B is 5: 4. Bus B departs from Miley Miley to Station A, and when it is 72km away from Miley Miley, bus A departs from Station A to Miley Miley Miley Miley. The ratio of the distance between the two trains and A station and bilibili is 3: 4, so the distance between A station and bilibili is () km.

1 1. There are 35 monkeys * * *, let's pick peaches together. When the Monkey King is away, a big monkey can pick 15 kg in an hour and a small monkey can pick 1 1 kg in an hour; When the Monkey King is present to supervise, each monkey, regardless of size, can pick 12kg per hour. One day, it was picked for eight hours, and only the first hour and the last hour were supervised by the Monkey King. As a result, * * * picked 4400 Jin of peaches, so among this group of monkeys, * * * had () little monkeys.

12. There are first prize and second prize in the math contest. It is known that: (1) The proportion of winners in schools A and B is 6 ∶ 5; (2) The total number of the two schools winning the second prize accounts for 60% of the total number of the two schools winning the prize; (3) The ratio of the number of students who won the second prize in A and B schools is 5 ∶ 6; Then the percentage of the number of people who won the second prize in a school to the total number of winners in the school is equal to ().