Several interesting math problems 1. Mom fried a dish with any two vegetables from tomatoes, green peppers, potatoes, beans and eggplant, and the collocation was different. How many dishes can she fry at most? There are two pairs of red socks and two pairs of black socks for the baby in the bag. How many socks can you take out at least to ensure the same color of a pair of socks? 3. A thread is folded in half and then folded in half, and finally cut from the middle. How many lengths are there in the cut wire? 6 athletes take part in the table tennis competition. Every two players have to play a game. How many games do they have to play at a time? A rectangular colored paper has four corners. How many corners are there after cutting off a corner along a straight line? 6. There are 16 children playing hide-and-seek on the playground, and 9 people have been caught. How many people are still hiding? Put the topic here first, and Weiwei will do it in the evening. Let's do it together and give the answer tomorrow. Last night, I asked Wei Wei to do the above questions. Except for the third question, my mother couldn't figure it out. Everything else was right. The answer is as follows: 1, tomato, green pepper, potato, beans, eggplant, stir-fry any two vegetables. Tomatoes can be fried with other four kinds of vegetables, four kinds of vegetables and green peppers can be fried with other three kinds of vegetables, three kinds of vegetables (fried with tomatoes), potatoes can be fried with other two kinds of vegetables, two kinds of vegetables (fried with tomatoes and green peppers), beans can be fried with eggplant, one kind of vegetables, 1 dish (all others have been fried). The dishes that mom can fry are: 4+3+2+ 1 = 10 (dishes) 2. There are four pairs of red socks and four pairs of black socks. When you take two, there may be one red and one black, but you can't. When you take the third one, it is either red or black. If the first two are different colors, the third one will definitely match one of the first two. So as long as you take three, you can definitely make a pair of socks of the same color. 3. The wire has two ends. Fold in half and then fold in half, and the middle becomes four lines, and eight lines are cut off. It turns out that a line has two heads. * * * is: 8+2 = 10 threads. Because the 1 line has two ends, the number of line segments after cutting is 5. 4. Six players compete, and every two will compete. No. 1 will play five games in one game with five other people, the second player will play four games in one game with four other people (exceptNo. 1), the third player will play three games in one game with three other people (exceptNo. 1), and the fourth player will play three games with two other people (No./) The fifth player will have a match with the last person (1, except players of 2, 3 and 4), and there will be a match of 1. They will have a match: 5+4+3+2+ 1 = 15 (match). 5. If the corner is cut from the middle of both sides of the corner, it becomes five corners, more than when it is not cut 1. If this corner is cut from one corner next to this corner to the middle of the other side, it is still four corners. If this tangent angle starts from one corner next to this corner to another, then there are only three corners. 6. There are 16 children playing hide-and-seek on the playground, and 9 people have been caught. And 16-9- 1 = 6 (person). Because 16 children include those who catch other children, he cannot catch himself. When Wei Wei did the third question, he didn't know what it meant to fold in half and then fold in half. I found a thread at home and asked him to fold it himself. I'll know when it's done. But I don't know how to calculate. You really have to cut the thread with scissors. Later, I was prompted to use the number of threads to calculate. But he turned around and realized a rule. That is, a line has two heads and only 1 segment; After being cut from the middle, there are 4 heads, which are changed into 2 segments =1+1; 1 After folding, it becomes 2 pieces, and the 2 pieces cut from the middle have 4 heads, while the original 2 pieces have 6 heads and become 3 pieces =1+2; After being folded in half twice, it becomes 4 pieces, the 4 pieces cut from the middle have 8 heads, and the original 2 pieces have 10 heads, which becomes 5 pieces =1+4; After being folded in half for three times, it becomes 8 segments, the 8 segments cut from the middle have 16 heads, and the original 2 segments have 18 heads, which becomes 9 segments =1+8; After being folded in half for four times, it was changed to 16, with 32 pieces of 16 cut from the middle and 34 pieces of the original 2 pieces, and changed to 17 =1+16; After being folded in half for five times, it becomes 32 pieces, and the 32 pieces cut from the middle have 64 heads, while the original 2 pieces have 66 heads, and the 33 pieces become =1+32; What rules do you see from it? Originally, there was 1 line, in which 1 has two lines after folding, four lines after folding, eight lines after folding, and four lines after folding 16. Fold five times, Add 32 yuan ................................................................................................................................................... .................... fold 1 time: 2 fold, 2 times: 2*2 fold, 3 times: 2*2*2 fold, 4 times: 2 * 2 * 2 fold, 5 times: 2 * 2 * 2 fold, 6 times: 2*2*2*2 …………………………………. I said, okay. Then you can discount it eight times. "Yes, I'll take you there." He speaks with confidence. "8 times 2, 4 times 2 equals 16, 16 times 16 equals 256" (2 * 2 * 2 * 2 * 2 = 256) plus the original 1, the total is 257. I applaud you, yes, and it is a verbal calculation. Because he can recite all the numbers below 20 by himself. 16 times 16 equals 256. He opened his mouth and came out. I remember when I entered the primary school interview, the teacher saw that he knew a lot, so he casually asked him what 15 times 15 was? Who knows that he can answer 225 without thinking. Surprised all the teachers. In the above problems, he also saw that cooking and ball games are the same kind of problems. But also found the law by doing the problem. No matter how many kinds of dishes there are, as long as two kinds of dishes are fried in one dish, the number of fried dishes is the number of dishes MINUS 1, and then they are added from big row to small row until 1. If there are 20 kinds of dishes, the number of stir-fried dishes is: (20-1=19)19+18+17+16+15+............. Wei Wei can also get the results quickly by oral calculation. When I give a child a question, I can usually find a general rule from it. The purpose is not to let him know how to calculate a problem, but a way of thinking. This time, he summed up the laws of the two topics entirely by himself. I didn't ask him at all. He didn't know about the disconnection at first, so I didn't ask him for more.

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