1. Simple order of understanding Olympic math problems in fourth grade primary school
1, arithmetic progression: Find the sum of arithmetic progression with the first term of 5, the last term of 93 and the tolerance of 4. Answer: Project number =(93-5)÷4+ 1=23.
(5+93)×23÷2= 1 127
2. If 1988 is expressed as the sum of 28 consecutive even numbers, what is the even number?
Answer: 28 even numbers are grouped into 14 groups, and 2 symmetrical numbers are grouped into one group, that is, the sum of the minimum numbers is:1988 ÷14 =142, and the difference between the minimum number and the number is 28-/kloc-0.
3. Find the sum of arithmetic progression with the first term of 5, the last term of 93 and the tolerance of 4.
Answer: Project number =(93-5)÷4+ 1=23.
(5+93)×23÷2= 1 127
2. The fourth grade of primary school understands the simple sequence of Olympic numbers.
1. Xiao Wang works in a factory. According to the factory regulations, he took two days off after five days of continuous work, and took two days off on March 2 and 3. So how many days off does Xiao Wang have in March? Please write down its rest date. Answer and analysis:
No.2, No.3, No.9, 10, No.65438+6, No.65438+7, No.23, No.24, No.30, No.31
2. Fill in five consecutive natural numbers in the following □ to make the equation hold.
□+□+□+□+□=30
3. There is a column numbered 3, 4, 8, 3, 4, 8, 3, 4, 8, ... What is the 25th number? What is the sum of these 25 numbers?
Answer and analysis: 3,123; 25÷3=8… 1, so the 25th number is 3.
Every third number is a period, 3+4+8= 15, and the 25th number contains 8 such periods, so the sum of these 25 numbers is: 15×8+3= 123.
25÷3=8… 1
3+4+8= 15
15×8+3= 123
3. The fourth grade of primary school understands the simple sequence of Olympic numbers.
Observe the following series, find out their arrangement rules, and say what series they are. ( 1) 1,2,3,4,5,6,……
(2) 1,3,5,7,9, 1 1……
(3) 10,20,30,40,50,60,……
(4)4, 10, 16,22,28,34,……
Dial:
(1) This is a series of numbers starting from 0, increasing gradually, and arranged in the order of our counting. It's called a natural sequence. From the second item, subtract each item from the previous item, and the difference is 1, which is also arithmetic progression.
(2) This is a series of numbers starting from 1, which is a series of continuous odd numbers. This is called an odd column. Starting from the second item, the difference between each item and the previous item is 2, which is also arithmetic progression.
(3) Observing this series, the former term plus 10 is equal to the latter term, that is, the second term minus the former term, and the difference is 10, and the difference is equal. This is arithmetic progression.
(4) In this series, starting from the second item, the difference between each item and the previous item is 6, and all the differences are equal, which is arithmetic progression.
Solution:
(1) is both a natural sequence and a arithmetic progression;
(2) It is both an odd-numbered column and a arithmetic progression;
(3) arithmetic progression;
(4) arithmetic progression.
4. Try to list the Olympic math problems in the fourth grade of primary school.
1, a math exam, it is stipulated that you get 5 points for doing a right question and 3 points for doing a wrong question. Xiao Wei did 10 and got 34 points. How many questions did he answer correctly? 2. Xiaoyan is 10 years old and her father is 40 years old. Her father is four times as old as Xiaoyan. A few years later, Dad was exactly twice as old as Xiaoyan.
3. My brother is 8 years old, and my brother 14 years old. How old are they when the sum of their ages is 48?
4. Squirrels pick 20 pine nuts every day in sunny days, 12 in rainy days and12 in rainy days, with an average of 14 per day. What is a rainy day?
5, 100 people eat 92 steamed buns, one adult eats 2, and two children eat 1, just finished eating. How many adults and children are there?
6. Two brothers went fishing, and * * * caught 52 fish, of which the younger brother caught 1, twice as much as the older brother. How many fish did they catch?
7. 10 RMB 45, 5 yuan RMB * * *, a total of 350 yuan. 1how much is 0 yuan? How much is 5 yuan money?
The kindergarten distributed a batch of oranges to the children. If each student in the big class gives 5, the rest is10; If you give 8 students to each small class, you will be short of 2. It is known that the number of small classes is three less than that of large classes. How many oranges are there in this batch?
5. Try to list the Olympiad math problems in the fourth grade of primary school.
1. The sum of the ages of eldest brother, second brother and third brother is 32 years old. Big brother is three years older than second brother and twice as big as third brother. How old are the three brothers 2, a math exam *** 10, Xiao Ming has finished, but only got 29 points. Because according to the regulations, you get 5 points for doing a right question and 2 points for doing a wrong one. Do you know how many questions Xiao Ming made wrong?
3. The sum of the ages of Party A and Party B is 99 years old, and Party A is 9 years older than Party B, and the two figures of Party A's age are exactly the age of Party B after swapping places. How old are Party A and Party B?
4. If the small square gives small glass balls, the number of glass balls of the two is equal; If Xiao Ming gives Xiao Fang a glass ball, Xiao Fang's glass ball is twice that of Xiao Ming. How many glass balls do Xiaoming and Xiao Fang have?
5. Students from a school go for an outing. At lunch, two students got 1 rice bowl, three students got 1 vegetable bowl, four students got 65 soup bowls, and * * * used 65 bowls. How many students are there?