1. Special topic of Olympic thinking training for primary school students 1
1, 765 × 2 13 ÷ 27+765 × 327 ÷ 27 solution: the original formula = 765 ÷ 27 × (213+327) = 765 ÷ 27.
2、(9999+9997+…+900 1)-( 1+3+…+999)
Solution: Original formula = (9999-999)+(9997-997)+(9995-995)+...+(9001-1)
= 9000+9000+...+9000 (500 9000)?
=4500000
3、 1998 1999× 1999 1998- 1998 1998× 1999 1999?
Solution: (19981998+1) ×199919981998×1999.
= 1998 1998× 1999 1998- 1998 1998× 1999 1999+ 1999 1998
= 1999 1998- 1998 1998
= 10000?
2. Primary school students' Olympic thinking training topic 2
1. There is a two-plate scale, with only one weight for 5g and one weight for 30g. Now, 300 grams of salt should be divided into three equal parts, at least called _ _ _ _ _ _ _ _. The truck and the car start from the same place and drive along the same road. The big truck will go for 2 hours first, and the car will catch up with the big truck after 5 hours. If the car travels 5 kilometers per hour, it will catch up with the big truck in 3 hours after departure. This car used to travel _ _ _ _ _ _ kilometers per hour.
3. The price of two commodities, A and B, is ***2200 yuan. Commodity A is priced at 20% profit, and commodity B is priced at 15% profit, both of which are sold at 90% price. The result is still profitable 1, 3 1 yuan. The cost of a commodity is _ _ _ _ _ _ _ yuan.
There are three piles of chess pieces, each pile has the same number of chess pieces, and only black and white chess pieces. There are as many sunspots in the first pile as there are Bai Zi in the second pile, and the sunspots in the third pile account for three-sevenths of all sunspots. Put these three pieces together and ask how many albinos are there.
5.a and B have a swimming competition. It is stipulated that two people start swimming at the same time from both ends of the 50-meter lane of the swimming pool until one catches up with the other, and the catching one wins. It is known that the velocities of A and B are 1.0m/s and 0.8m/s respectively. Q (1) How long will it take for A to catch up with B after the game starts? (2) How many times did two people meet head-on when A chased B?
3. Special topic of Olympic thinking training for primary school students 3
1. In a club, there are two kinds of members: honest people always tell the truth and liars always tell lies. Once we talked to four members of the club and we asked them, "Who are you, honest people?" ? Or a liar? The answers of the four men are as follows: The first man said, "We are all liars. "
The second man said, "Only one of us is a liar."
The third man said, "Two of the four of us are liars."
The fourth man said, "I am an honest man."
Please judge, is the fourth person honest?
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Party A, Party B and Party C each said a sentence, and each sentence was either right or wrong. A said, "Both B and C are lies." B said, "I never lie." C said, "What B said is a lie." Can you tell whose words must be wrong?
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There are three kinds of people, honest people always tell the truth, liars always tell lies, and normal people sometimes tell the truth and sometimes tell lies. Among three people, A, B and C, there is an honest man, a liar and a normal person.
A said, "I am normal."
B said, "A is telling the truth."
C said, "I am not a normal person."
Q: What kind of people are A, B and C?
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4. Special topic of Olympic thinking training for primary school students 4
1, sunset, red sun, I put the chicken in the cage. Half of the chickens are in cages, five are catching bugs, and the other five are buzzing around me. Children, let's count. How many chickens are there in the cage? 2. It takes 1 minute for a cat to eat a fish. So, how many minutes does it take for 100 cats to eat 100 fish at the same time?
It takes five minutes for five children to eat five apples at once. At this rate, how many minutes will it take for 10 children to eat 10 apples at the same time?
4. Xiaohua has 10 red balloons, and Xiaohua has 8 yellow balloons. Xiaohua exchanged four red balloons for three yellow balloons for Xiaohua. How many balls does Kobanawa Xiaohua have now?
5. 13 children have caught five "chickens" by playing the game of "the eagle catches the chicken". How many didn't get caught?
5. Special topic of Olympic thinking training for primary school students 5
1. The teacher wrote down 13 natural number on the blackboard and asked Xiao Wang to calculate the average (keep two decimal places). The answer calculated by Xiao Wang is 12.43. The teacher said that the last figure was wrong and all the other figures were right. The correct answer should be _ _ _ _ _. Two fifths of Lao Wang's weight is equal to two thirds of Xiao Li's weight. 3/7 of Lao Wang's weight is lighter than 3/4 of Xiao Li's weight 1.5 kg, so Lao Wang's weight _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ kg.
3. In one exam, 17 students got 100 in math, 100 in Chinese, 100 in both subjects and 100 in at least one of the two subjects. There are _ _ _ _ _ _ _ _ people in Class 45 who failed in both subjects 100.
4. A fruit shop bought six baskets of fruits with bananas and oranges weighing 8, 9, 16, 20, 22 and 27 kg respectively, and only sold one basket of oranges that day. In the remaining five baskets, bananas weigh twice as much as oranges. I asked if the basket bought by the fruit shop that day was a banana.
There are 100 students going to a park 33 kilometers away from the school. The walking speed of the students is 5 kilometers per hour. There is only one car that can take 25 people in the school, and the speed is 55 kilometers per hour. In order to get to the park in the shortest time, we decided to combine walking and cycling, so the shortest time is _ _ _ _ _ _ _.