Divided by 7, 1 has 8 numbers.
There are seven numbers divided by seven and two.
There are seven numbers divided by seven and three.
There are seven numbers divided by seven and four.
Seven divided by five has seven numbers.
There are seven numbers divided by seven and six.
Seven is divisible by seven.
Divide 1-50 into the above 7 groups.
So that the sum of two numbers can't be divisible by 7, 1-6 groups of numbers can be extracted, but 1 and 6 can't appear at the same time, 2 and 5 can't appear at the same time, 3 and 4 can't appear at the same time, and only 7 groups of data can be extracted 1.
So you can extract all the data of 1, 2, 3, plus one in the seventh group, so a * * * can extract 23.
Xiao Ming and both are students of Teacher Zhang. Teacher Zhang's birthday is the n day of M month. Both of them know that Teacher Zhang's birthday is one of the following 10 groups. Teacher Zhang tells Xiao Ming the value of m and Xiao Qiang the value of n. Teacher Zhang asked them if they knew when his birthday was.
March 4, March 5, March 8
June 4, June 7
September1September 5
65438+February165438+February 2nd 65438+February 8th
Xiao Ming said: If I don't know, Xiao Qiang certainly doesn't know.
Xiao Qiang said: I didn't know at first, but now I know.
Xiao Ming said: Oh, I know that, too.
Please infer from the above conversation when is Teacher Zhang's birthday?
Reference answer:
Xiao Ming said: If I don't know, Xiao Qiang certainly doesn't know.
Show that the number in Xiao Ming's hand is 3 or 9.
Xiao Qiang said: I didn't know at first, but now I know.
This shows that the number in Xiao Qiang's hand is not 5.
Xiao Ming said: Oh, I know that, too.
Explain that the number in Xiao Ming's hand is not 3.
To sum up, the number in Xiao Ming's hand is 9, and that in Xiao Qiang's hand is 1.
Answer: September 1
Percentage application problem. A job can be completed in three days, and B can be completed in two days. How many days does it take for two people to cooperate? What percentage of work did each of them do when they finished?
2. The bookstore sent a children's story book, which sold 30% on the first day and 120% on the second day, 30 more than the first day. How many copies of this story book have arrived from the bookstore?
1. A farm warehouse shipped out 162 tons of fertilizer and brought in 142 tons. At this time, the chemical fertilizer in the warehouse is 5% less than before. How many tons of chemical fertilizer are there in the warehouse?
3. In the first quarter of Shazhou Paper Factory, the output of newsprint in that month increased by 10%. It is understood that the output of newsprint in February was 220 tons. How many tons of newsprint were produced in the first and third months?
A 2400-meter-long canal was built in Hongshui Village. 37.5% of the total length was completed in the first week, and the remaining 1 1/20 was completed in the second week. How many meters does it take to complete this task?
5. Master and apprentice process a batch of parts at the same time. When completing the task, the master added 65% of these parts, while the apprentice processed 24 less than the master. How many parts have been processed by master and apprentice?
6\X field 65438+ 10, the industrial output value in October was 900,000 yuan, 20% less than that in February. What is the industrial value in February?
7\ Xiaoming reads books. On the first day, he read 40% of the book. On the second day, he read a third of the book. On the third day, he read 80 pages. How many pages are there in this book?
8. There are three classes in grade six in a school. The number of students in Class A is 1, which is 2/5 times that of Class B. Class B is 20% less than Class C. There are 56 students in Class A. How many students are there in Grade 6?
9. The total grain output of Yuejin Village last year was 6.5438+0.8 million Jin. Strive to increase 15% this year compared with last year. How many kilos can the total grain output reach this year?
10. The number of boys in Cangding Primary School is exactly equal to 60% of the number of girls. It is understood that there are 480 boys in this school. How many students are there in this school?
The last few have no answers, so don't mind! ! !
I hope I can help you! ! !
I hope to consider adopting it