Examination questions of primary school mathematics competition (sixth grade)

1. A three-digit number divided by 9 plus 7, divided by 5 plus 2, divided by 4 plus 3. Such a three-digit * * has _ _ _ _ _.

I bought 83 Jin of oranges, apples, bananas and persimmons from 2 yuan, 3 yuan, 2 yuan and 4 yuan, and spent 228 yuan. As we all know, buying oranges is as expensive as buying apples, and buying persimmons is twice as expensive as buying bananas. Then oranges bought _ _ _ _ _ _ _ kilograms, and apples bought _ _ _ _ _ _ _ kilograms.

3. According to the provisions of the tax law, if the income from one-time labor service is less than that of 800 yuan, it shall be exempted from income tax. If you exceed 800 yuan, you have to pay income tax. Specific standards are: 800 ~ 2000 is 10%, 2000 ~ 5000 yuan is 15%, and 5000 ~ 10000 yuan is 20%. The tax amount of a person's income from a labor service is 1300 yuan, and his after-tax net income from the labor service is _ _ _ _ _ _ _.

Octal addition is to convert each octal into one, for example, 13+6 = 2 1, 77+4 = 103. In the following octal addition vertical formula, the six numbers A, B, C, D, E and F are just composed of the six numbers 1, 2, 3, 4, 5 and 6, so there is an _ _ _ _ _ _ * addition formula that meets the conditions in the question.

6. 1 By 2000, the maximum number of _ _ _ _ _ can be taken out, so that the sum of any three of these numbers cannot be divisible by 7.

7. The six rectangles with an area of 1, 2, 3, 4, 5 and 6 are arranged as shown below, and the shaded area is _ _ _ _ _.

8. The cost of a commodity is 80 yuan per piece. If you sell them at 100 yuan each, you can sell them at 1000 yuan. When the price of this commodity increases by 1 yuan, the sales volume will decrease by 20. In order to make the biggest profit, the price should be set at RMB _ _ _ _ _ _.

9. A bug climbs from A to B. If its speed increases by 1 meter per minute, it can arrive 15 minutes earlier. If its speed is increased by 2 meters per minute, it can arrive 15 minutes earlier. The distance between a and b is _ _ _ _ _ meters.

10. The alcohol concentration in bottle A is 70%, the alcohol concentration in bottle B is 60%, and the alcohol concentration after mixing the two bottles is 66%. If two bottles of alcohol are mixed with 5 liters each, the concentration after mixing is 66.25%. Q: It turns out that bottles A and B have _ _ _ _ _ liters and _ _ _ _ _ liters respectively.

1 1. Use the nine numbers 1, 2, 3, 4, 5, 6, 7, 8, 9 to form the smallest nine digits divisible by 1 1. This nine-digit number is _ _ _ _ _ _ _.

12. Arrange the 625 natural numbers of 1 ~ 625 clockwise into a circle. Clockwise from 1 erase 1, keep 2, then erase 3, 4, keep 5, erase 6, keep 7, and then erase 8, 9, keep 10 ... so erase one number, keep one number, erase two numbers and keep one number; Erase one more number, keep the next number, erase two numbers, keep one number ... all the time, and the last number left is _ _ _ _ _ _ _.