2. Xiaohua took part in the math contest, with the question * * * 10. It is stipulated that the correct answer is given ten points, and the wrong answer is deducted five points. Xiaohua answered all ten questions and got 85 points. How many questions did Xiaohua answer correctly?
3、2,3,5,8, 12,(),()
4、 1,3,7, 15,(),63,()
5、 1,5,2, 10,3, 15,4,(),()
6. What numbers do ○, △, ☆ represent respectively?
( 1)、○+○+○= 18
(2)、△+○= 14
(3)、☆+☆+☆+☆=20
○=()△=()☆=()
7、△+○=9△+△+○+○+○=25
△=()○=()
8. There are 35 sweets. In the order of naughty-smile-tintin-winter and winter, everyone sends one at a time. Think about it. Who got the last one?
9. Naughty began to have money in 300 yuan, so he went to 56 yuan to buy books, 128 yuan to buy stationery. How much money did naughty leave behind?
10, how many minutes does it take for five cats to eat five mice and 20 cats to eat 20 mice?
Question and answer of second grade Olympic mathematics.
1. Aunt Zhang and Aunt Li bought a basket of apples, weighing 20 Jin. Aunt Zhang took out 10 kg from the basket, and the empty basket weighed 1 kg. How many Jin did Aunt Li buy? How many grams?
Answer: Aunt Li bought apples 20-10-1= 9 (kg)1000g× 9 = 9000g. Aunt Li bought apples 9 kg, that is, 9000g.
2.20 Children line up, mathematics ranks second in the front, and Sisi ranks fourth behind learning. So Sisi ranks from the back to the front?
Answer: Mathematics ranks second from the front and Sisi ranks fourth from the back, that is to say Sisi ranks second +4 = 6 (1) from the front and 20-6= 14 (1) from Sisi's right, so Sisi ranks 14+ 1 = 654.
The small animals in the forest held a sports meeting. Pork chop 13, rabbit ranked fifth. How many small animals does a pig have to surpass to be tied for fifth place with a rabbit?
Answer: There are seven small animals between the rabbit and the pig, so the pig only needs more than seven small animals.
4. Use ○, ★ and △ to represent three numbers, including ○+○ = 15, ★+★ =12, △+△ = 18, ○+★+△ = ().
Answer: The ○, ★ and △ in the above formula represent three numbers respectively. According to the sum of three identical addends, they are 15, 12 and 18, so we can know that ○=5, ★=4, △ = 6,5+4+6 =15.
Mother bought some chocolates, gave them to her neighbor's little sister, and then took them home. Xiaoya ate half of it first, and then gave the rest to her brother. At this time, there is 1 chocolate. How many chocolates did mom buy?
Answer: "My brother ate the remaining half, and there was 1 chocolate." The remaining half is 1, and the younger brother had 1×2=2 (block) before eating, that is, after Xiaoya ate half, Xiaoya had 2×2=4 (block) before eating, and her mother "took it home for her neighbor's little sister", so a * * had 4+2.
6. Little monkeys like bananas. The Monkey King picked 30 bananas. After he gave it to the little monkey 15, China monkey gave him eight bananas to please him. At this time, they have as many as three bananas. Let's count, how many bananas did the little monkey and the China monkey pick at first?
Answer: the Monkey King gave the monkey 15 bananas, and the monkey gave the Monkey King 8 bananas. There are 23 bananas in the Monkey King now, as many as the three of them. The original banana of monkey is 15 less than 23, which should be 8. The raw bananas of monkeys are 8 more than 23, which should be 3 1.
Xiao Ming has three numbers in his mind, and the sum of these three numbers is equal to the product of these three numbers. Do you know what the three numbers that Xiao Ming thinks of are?
Answer: Guess: The three numbers that Xiao Ming thinks are 1, 2, 3.
8. Grandma keeps 20 chickens in five cages, and the number of chickens in each cage is different. How did Grandma put 20 chickens in five cages?
Answer: Step 1: Find out how many chickens are in five cages, so that the number of chickens in each cage is different. 1+2+3+4+5= 15 (only).
Step 2: Put 15 chickens according to the formula in step 1, and then put the remaining 5 (20- 15=5) chickens into 5 cages as required (the number of chickens in each cage is different). * * * There are seven different answers.
① Put the remaining five chickens in any cage, and you can get five answers:
6+2+3+4+5=20; 1+7+3+4+5=20; 1+2+8+4+5=20;
1+2+3+9+5=20; 1+2+3+4+ 10=20。
② Divide the remaining five chickens into two groups: 1 chicken and 4 chickens, and put them in two cages respectively, and you can get two answers:
1+2+3+8+6=20; 1+2+7+4+6=20。
9. This new computer company has 87 computers. I sold 19 units in the morning and 26 units in the afternoon. How many computers are left? (Answer in two ways)
Answer: Scheme 1: subtract the number of computers sold in the morning from the total number of computers, and the formula is: 87- 19=68 (units). Then subtract the remaining computers sold in the afternoon from the remaining computers, and the formula is: 68-26=42 (units).
Option 2: We can add up what we sold in the morning and afternoon, figure out how much we sold, and then subtract what we sold from the total number of computers in the company, which is the rest. We can make a comprehensive formula for this part: 87-( 19+26)=42 (Taiwan).
A: There are 42 computers left.
10. Master Wang made 80 cakes and sold them for the first time 17 and for the second time, 25 cakes were sold. How much bread is left?
Answer: Add up the total number sold first, that is 17+25=42 (pieces). If you subtract the bread made by Master Wang from what he sells, the rest is 80-42=38 (blocks).
A: There are 38 left.
The second year of Olympic Mathematics, the topic is 3 1. Xiaoming saw in the mirror that it was 5: 35 on the clock. Do you know what time it is?
2. Six ducklings line up, one in three teams, with three ducklings in each team. How to line up?
3, 8 people eat, each person 1 rice bowl, two people a dish bowl, four people 1 soup bowl, a * * *, how many bowls are there altogether?
4. Xiao Liang is sitting on the tour bus on the circular runway. He found six cars in front and six cars in the back. Excuse me: How many cars are there on the runway?
Suppose there is a plant that grows twice as tall every day. 20 days is exactly 20 centimeters high. Excuse me: When did it grow to 5 cm?
Xiaoming keeps some ducks at home. Know how many ducks there are. Think about it. "Half of the ducks are in the water, and half of them will go into the water if they are divided by 2, and the rest 15 will eat sundries around Xiao Ming. How many do you say? "
7, a division problem, the divisor is 6. Xiao Ming reversed the ten digits and single digits of the dividend, and the quotient of the dividend was 4. What is the correct quotient?
8, a bottle of oil, even 800 grams, eat half of the oil, even the bottle, there are 550 grams left. How many grams of oil are there in the bottle How many grams does this empty bottle weigh?
9 1 weight of goose+weight of 3 chickens =1weight of 0 ducks.
Weight of 8 chickens =1weight of 6 ducks.
1 weight of a goose = () weight of a duck.
1 goose = () the weight of a chicken.
10, 1 watermelon +2 pears = 16 apples.
5 pears = 10 apples 1 watermelon = () apples
1 watermelon = () pear
The second grade Olympiad math problem is 4 4 1. The weight of an apple is equal to the weight of an orange plus a strawberry, and the weight of an apple plus an orange is equal to the weight of nine strawberries. Excuse me, the weight of an orange is equal to the weight of several strawberries.
There is a balance and nine weights, one of which is lighter than the other eight. How many times do I have to say it before I can find the lighter one?
43. According to the law:
( 1)5432 1 432 15 32 154 ( ) 15432 1
(2) 1,2,3(7) 2,3,4( 14) 3,4,5()
(3) 1,4,7, 10,( ), 16,,( )
(4) 1,2,3,7, 1 1, 16,( ),29
(5)2,5,4,5,6,5,( ),5
(6)7,8, 10, 13, 17,( )28
44. 10 One hundred is (), and 10000 includes () one thousand.
The highest digit of 45,3572 is (), which is pronounced as () and 9050 is written ().
46, a 2 cent coin weighs about 4 (); Xiao Ming is seven years old and weighs about 28 ().
47 and 90 have () ten, and 290 has () ten.
48. 6 out of 100 yuan is more than 6 out of 10 yuan ().
49. Forty-nine apples are distributed to nine children on average. Each child has () apples, and there are () apples left.
50. Judge whether it's true or not (tick "√" for the right and "×" for the wrong)
(1), a number divided by 4, the largest remainder is 3. ( )
(2、48÷3×2 = 48÷6 ( )
(3) The weight of an apple 120kg. ( )
(4,000 people must be tens of thousands on the right. ( )
Five problems in the second grade Olympic Mathematics
1. Mingming and Lulu collected some stamps. Clearly found that if he gave Lulu four stamps, they would have the same number of stamps. Lulu found that they always have 12 stamps, so obviously there are () stamps and Lulu has () stamps.
2. Monkey Lele and Tintin went to pick bananas. Lele picked 10, Tintin picked 6, and Lele gave Tintin (), so they had as many bananas.
There are three trees, and there are the same number of birds on them. At this moment, a hunter came and the birds panicked. Three birds fly from the first tree to the second tree and three birds fly from the second tree to the third tree. At this time, there are more birds on the third tree than in the first lesson ().
answer
1 analytic addition and subtraction application, error-prone: obviously 8 more than Lulu. Excluding the extra eight, they are as many as two, 12-8=4, Lulu has 4÷2=2, and obviously there are 2+8= 10 (sheets).
The answer is obviously10; Lulu has two.
2 Analysis Lele is more than Tintin 10-6=4, and Lele wants to give Tintin 4÷2=2.
Two answers.
The analysis of the topic seems to have taken a detour, but as long as two points are clear: the first tree and the third tree are as many as before; Later, the first one lost three and the third one got three. Then the third tree should be six more than the first tree.
There are six answers.
Fill in the blanks according to the following four formulas, can you find the rules, and then fill in the appropriate numbers in the box.
1×5+4=9=3×3
2×6+4= 16=4×4
3×7+4=25=5×5
Answer:100x104+4 =10404 =102x0/02.
The most important rule in the four formulas is that the difference between the two factors is 4, so there is10×14 =144 =12×12.
102× 102 = 10404, 10404-4 = 10400 = 100× 104,
So there is100×104+4 =10404 =102×102.
Sophomore olympiad 7 1. Find the circumference skillfully.
When I was a sophomore, I skillfully asked for the circumference of the Olympic Games: I clearly used a 30-decimeter-long black line to set a black border for my photo. The width of this rectangular photo frame is 6 centimetres. Do you know how long this photo frame is?
Answer: 30÷2-6=9 (decimeter)
To sum up, the length of this black line is the circumference of this rectangle. Read the known conditions and let the students understand that the perimeter and width of this problem are known. What is the length of this rectangle? There are two solutions:
Method 1: Subtract two widths from the perimeter to make two lengths, and then divide by two to make a long length. The formula is: (30-6×2)÷2=9 (decimeter).
Method 2: Divide the perimeter by 2, that is, the length plus the width, and then subtract the width, that is, the length of the rectangle. Formula: 30÷2-6=9 (decimeter) By comparison, the second method is simpler.
Find the circumference skillfully
After two squares of the same size are put together into a rectangle, the circumference is 4 cm less than the sum of the original two squares. What is the circumference of the original square?
Answer: 2×4=8 cm.
Two squares are put together to form a rectangle, and the sum of the eight sides of two squares minus two sides is 4 cm, so the length of one side is 4÷2=2 (cm). The circumference of a square is 2×4=8 cm.
The first question of 8 questions in the second grade Olympic Mathematics: multiple choice questions.
Xiaoming went to the orchard and picked 18 pears and 3 apples. How many times more pears did he get than apples?
Question 2: Fruit.
Lily's family bought 56 apples, seven times as many as oranges. How many more apples did Lily buy than oranges?
The third question: planting trees
The distance between two telephone poles along the road is 100 meter. Now, if you want to plant trees between these two poles, how many trees will be planted per 10 meter?
answer
The answer to the first question is:
Solution: 18÷3=6
The answer to the second question is:
Answer: 56÷7=8 (pieces) 56-8=48 (pieces)
The answer to the third question:
Solution:100 ÷10 =10/0-1= 9 (tree)
Sophomore olympiad math problem 9 1. application problem
Xiao Qiang took part in the shuttlecock kicking competition. There are 20 participants. Before the game, every two children shook hands. How many times did Xiao Qiang shake hands?
Answer: Xiao Qiang wants to shake hands with everyone except himself, so he has to shake hands 20- 1= 19 times.
Please note that Xiao Qiang doesn't have to shake hands with himself.
2. Incompatibility principle
A class of children worked out two oral arithmetic problems. The first one who answered correctly was 19, the second one was 17, and the second one was 10. How many children are there in this class?
Answer:
Method 1:
There are 10 children who are correct in both questions, so only 19- 10=9 children are correct in the first question, and only 17- 10=7 children are correct in the second question. So there are 9+ 10+7=26 children in this class.
Method 2:
When we calculate the number of children who answer the first question and the second question correctly, we notice that the children who answer the two questions correctly are counted once. So there are19+17-10 = 26 children in this class.
Summarize that children can increase their understanding of the topic according to their own class situation. Mathematics often comes from life.
On the second day of junior high school, I typed 10 A and B at the same time, and typed 240 words in 2 minutes. It is known that A typed 10 more words per minute than B. How many words did A and B type per minute?
Answer and analysis: A (240÷2+ 10)÷2=65 (pieces)
B 65- 10=55 (unit)
To sum up, we must first understand that 240 words were typed in 2 minutes, and then both parties typed 240 ÷ 2 = 1 minute. This is a typical sum-difference problem.
Method 1: A (240÷2+ 10)÷2=65 (unit) B 65- 10=55 (unit).
Method 2: B (240÷2- 10)÷2=55 (pieces) A 55+ 10=65 (pieces).