The only way that 10 can be written as the sum of 4 different counting numbers is 1+2+3+4. In how many different ways can 15 be written as the sum of 4 different counting numbers?
Number 6 is written as sum of two positive integers in three different ways: $6=1+5=2+4=3+3.$ (order does NOT matter). That is, there are exactly three different pairs of positive integers that add to make six. How many pairs of positive integers that add to make 1000?
Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
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Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
Combinatorics
21. 15 students join a competition. Only top 5 students can be promoted to next round. How many different way(s) of promotion advance is / are there?
Different way: Cách khác nhau.
22. It is known that there are 8 classes of grade 5 in a primary school. At least how many students are there in grade 5 to ensure there exist 41 students in the same class?
At least: Ít nhất; Ensure: Chắc chắn; Exist: Tồn tại.
23. Choose 3 digits from 1, 2, 3, 4, 6, 8 and 0 to form 3-digit numbers. How many even number(s) greater than 300 is / are there? (The repetition of digits is not allowed)
Digit: Chữ số; 3-digit number: Số có 3 chữ số; Even number: Số chẵn; Greater than: Lớn hơn; Repetition of digits is not allowed: Các chữ số không được lặp lại.
24. A flight of stairs has 10 steps. Peter can go up for 1 step, 2 steps or 3 steps each time. How many way(s) is / are there for Peter to go up the stairs?
Step: Bước; Way: Cách.
25. Numbers are drawn from 80 integers 20 to 99. At least how many number(s) is / are drawn at random to ensure that there are two numbers whose sum is 85?
Integer: Số nguyên; At least: Ít nhất; Random: Ngẫu nhiên; Ensure: Chắc chắn; Sum: Tổng.
~ End of Paper ~
Consecutive counting numbers are grouped as follows: (1);(2,3) ;(4,5,6);(7,8,9,10);.....
there is one number in the first group, 2 numbers in the second group,3 numbers in the third group,.....
The sum of all numbers in the 100th group is.....
From 4 letters ab18 one can make all 18 numbers with 4 digits. (In a number, each digit is written only once.) The sum of all 18 possible numbers is 90216. Find a and b.
Number 6 is written as sum of two positive integers in three different ways: $6=1+5=2+4=3+3.$ (order does NOT matter). That is, there are exactly three different pairs of positive integers that add to make six. How many pairs of positive integers that add to make 1000?
Các bạn giải nhanh giùm mình nhé để mình con đi thi
đề là:Số 6 được viết bằng tổng của hai số nguyên dương theo ba cách khác nhau: $ 6 = 1 + 5 = 2 + 4 = 3 + 3. $ (thứ tự KHÔNG quan trọng). Nghĩa là, có chính xác ba cặp khác nhau của số nguyên dương mà thêm để bằng sáu. Có bao nhiêu cặp số nguyên dương cộng thêm bằng 1000?(ý là có mấy số cộng lại = 1000 )
à quên:Số 6 được viết bằng tổng của hai số nguyên dương theo ba cách khác nhau: $ 6 = 1 + 5 = 2 + 4 = 3 + 3. $ (thứ tự KHÔNG quan trọng). Đó là, có đúng ba cặp khác nhau của các số nguyên dương mà thêm để bằng sáu. Có bao nhiêu cặp số nguyên dương mà thêm để bằng 1000?
How many different 3-digit whole numbers can be formed using the digits 4, 5, 0 and 8, assuming that no digit can be repeated in a number?
Làm thế nào nhiều người khác nhau 3 chữ số số nguyên có thể được hình thành bằng cách sử dụng chữ số 4 , 5, 0 và 8 , giả định rằng không có chữ số có thể được lặp đi lặp lại trong một số?
bao nhiu zậy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
trả lời giúp mk
How many different 3-digit whole numbers can be formed using the digits 4, 5, 0 and 8, assuming that no digit can be repeated in a number?
The average of five different natural numbers is 4. If the different between the largest and smallest of these numbers is as large as possible, what is the average of the other three numbers?