1. Math problem _ The hours, minutes and seconds of the clock completely coincide within 24 hours a day. How many times do the hour hand, minute hand and second hand of a clock completely coincide? When are they? How did you work it out?
2. There are 24 kilograms of oil divided into 24 kilograms of oil. There is only one 5 kg container today, 1 1 kg, 13 kg. How can I divide the oil into three equal parts?
3. Which athlete is left in the end? Inverse math problem 1 No.50 athletes line up in turn. The coach ordered: "odd athletes stand up!" " "The rest of the athletes lined up again. The coach ordered again: "odd athletes stand out!" "So, there is only one person left in the end. What's his date? If the coach's order is "even the athletes stand out!" "Who is the last one?
4. Confusion in calculating age Xiaoming said to his younger brother: When I grow up to your age, you will be 3 1. Brother said, yes, when I was your age, you were only one year old. Q: How old are Xiao Ming and his brother now?
It is a loss for the boss for young people to buy gifts. One day, a young man came to boss Wang's shop and bought a present. Gift cost 18 yuan, price 2 1 yuan. The young man took out 100 yuan to buy this gift. Boss Wang didn't have any change at that time, so he used this 100 yuan to change 100 yuan for the neighborhood and gave the change to the young man 79 yuan. But later, the neighborhood found that 100 yuan was counterfeit money, and Boss Wang had no choice but to return 100 yuan to the neighborhood. Excuse me: How much did Boss Wang finally lose in this transaction?
6. Calculate Xiao Dong's grades. In a competition, Xiaodong's Chinese and natural achievements add up to 197, Chinese and mathematics add up to 199, and mathematics and natural achievements add up to 196. Xiaodong, which subject got the highest score? How is Xiaodong's performance in all subjects? According to the three known conditions given in the title, it is not difficult to see that the Chinese score is the highest. How to find out the results of three subjects?
7. Judge which way to take the math problem. A person stands at a fork in the road, leading to country A and country B respectively. People in both countries are very strange. People in country A always tell the truth, while people in country B always tell lies. There is a China A and a China B at the intersection, but I don't know their real identities. Now that man is going to country B, but he doesn't know which way to go. He needs to ask these two people. Just asking. How did he judge which way to go?
8. Math puzzle: Calculate the unit price of three kinds of tables. There are three kinds of tables in the furniture store, and the prices are as follows: 1. Their unit prices are different; Their unit price adds up to 4000 yuan; 3. The second table is cheaper than the first table, 400 yuan; The unit price of the third table is twice that of the second table. So what is the unit price of these three kinds of tables?
Answer: 1. Ideas to solve the problem: Obviously, once after 1: 05, once after 2: 00, once after 3: 00, once after 4: 20, once after 5: 25, once after 6: 30, once after 7: 35 and once after 8: 40. In addition, the time spent between two adjacent overlaps is the same, that is, 12/ 1 1 hour. Exactly 0: 00,12/1,24/ 1 1, 36/ 1 1, 48/ 1. 96/ 1 1, 108/ 1, 120/1,12. Interestingly, the point 1 1 is exactly the inscribed circle on the positive side of 1 1, and there is a vertex at the point 12.
2. First, fill the 13 kg container, fill the 5 kg container with the remaining 8 kg, pour it into the 1 1 kg container, and pour the oil from the 5 kg container back into the big container; Take out the oil from the big container, fill the container with 13 kg, then pour out 5 kg, leaving 8 kg; If the oil in the 5kg container is poured back into the big container, the oil in the big container is also 8kg.
3. Problem-solving ideas: This question adopts reverse deduction method. Odd athletes are out, the coach has to give five orders, and finally there is only one person left. This person ranks in the top 2 of the next 5 singles, the top 4 of the next 4 singles, the top 8 of the next 3 singles, the top 2 singles 16, and the top 32 of the next 1 singles. He is the No.32 athlete. When a pair of athletes line up, it is simply the 1 athlete. A: The former is athlete No.32, and the latter is athlete 1.
4. Solution: Let the elder brother's age be G and Xiaoming's age be D, then G(g-d)=3 1, and D-(g-d)= 1. Solve the equation and get: g=2 1, d= 1 1. Answer: Xiaoming 1 1 year-old, brother 2 1 year-old.
Boss Wang finally lost 97 yuan money in this transaction.
6. We can think with "holistic thinking", because this problem belongs to the "circular" problem of finding the numbers of A, B and C, given "the sum of two numbers A and B, the sum of two numbers B and C, and the sum of three numbers C and A". When solving problems, first add three pairwise sums to get the "pairwise total score" of three subjects (the score of each subject is calculated twice), then divide by 2 to get the total score of three subjects (once), then subtract the natural total score of Chinese from this total score to get the math score, subtract the natural total score of Chinese mathematics to get the natural score, and then subtract the natural total score of Chinese mathematics to get the Chinese score. The step-by-step answer is as follows: 1 Total score of three subjects: (197199196) 2 = 296 (points); 2. The scores of the three subjects are: Chinese 296- 196= 100 (points), natural 296- 199=97 (points), and mathematics 296- 197=.
7. If A is a local and telling the truth, ask A: If I ask B which way is safe, which way will he point? He pointed out that the way B said it was wrong and the other way was right. 2. If A is a native of B and tells a lie and asks A the same question, because B is telling the truth and A will have the opposite answer to B, then the other way is correct.
8. The unit price of the first table is 1300 yuan, the second table is 900 yuan, and the third table is 1800 yuan. Assuming that the price of the first table is lower than that of 400 yuan, the price of the first table is the same as that of the second table. At this time, if the total price is reduced by 400 yuan, it will become 3600 yuan, which is the total price of four second tables. 300/4=900 yuan, 900*2= 1800 yuan, 900400= 1300 yuan.