A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
P/s: Math Violympic: Grade 5, Round 2
A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
ok
1 to 9 have 9 numbers
10 to 99 have 90 numbers
100 to 250 have 151 numbers
in the book have 250 numbers
dich
1 toi 9 co 9 chu so
10 toi 99 co 90 chu so
100 toi 250 co 151 chu so
trong cuon sach co 250 chu so
nho tink cho minh nha
Số trang sách có 1 chữ số là: 9 - 1 + 1 = 9 (trang). Suy ra: Số chữ số của những trang này là: 9 (chữ số)
Số trang sách có 2 chữ số là: 99 - 10 + 1 = 90 (trang). Suy ra: Số chữ số của những trang này là: 90 x 2 = 180 (chữ số)
Số trang sách có 3 chữ số là: 250 - 100 + 1 = 151 (trang). Suy ra: Số chữ số của những trang này là: 151 x 3 = 453 (chữ số)
Tổng các chữ số của quyển sách là: 9 + 180 + 453 = 642 (chữ số)
Câu 1 :Each of cars can take 8 people. How many cars needed to take 124 people?
Câu 2 : How many integer numbers between 200 and 300 are there for which the hundreds digit equals the sum of the other two digits?
Câu 3 : The average of five numbers is 20. The average of the five number is 18 when one of the numbers is chaned to 4. What is the orginal value of the changed number?
Câu 4 :A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
Câu 5 : Find A, if A is 3 less than the average of 48; 55; 29 and A. The value of A is…
Câu 6 : The sum of denominator and numerator of a fraction is 121 and the fraction is equal to 4/7. Find the denominator of the fraction?
Câu 7 : The sum of two numbers is equal to 77. If the first number is multiplied by 8 and the second by 6, the two product are equal. The larger of these numbers is…
Câu 8 : Which is the greatest 2 - digit number divisible by 2, 3 and 4?
Câu 9 : Calculate: (1 + 2/5) x 6/7.
Câu 10 : Give the number sequence: 1, 4, 7, 10, 13, … Find the 15th term of the number sequence.
câu 1:16 ; câu 2 : ai mà biết được
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 ~
là seo pạn?mik hem hỉu??????????????????????
Đọc cái bài mà mún trầm kẻm!
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 ~
The numbers of digits used to write all the page numbers in a book is 35.How many pages is the book in total?
Cần 35 chữ số để đánh một số trang sách. Hỏi có tất cả bao nhiêu trang sách?
61 trang . bạn có thể tham khảo bài trong câu hỏi tương tự .
PART 1: NUMBER AND DIGIT
Answer the questions
How many digits are there in the number 7,429?
Name the digits of the numbers 7,429?
How many digits are there in the number 264?
Name the digits of the numbers 264?
7,429 has 4 digits
it: 7, 4, 2, 9
264 has 3 digits
it: 2, 6, 4
In a number sequence : 1 , 1 , 2, 3 , 5 , 8 , 13 , 21 , ... , starting from the third number , each number is the sum of the two numbers that come just before it . How many even numbers are there among the first 1000 numbers in the number sequence ?
Write the words in number form which consist of: 7 hundred thousands, 6 thousands, 3 hundreds, 4 tens and 2 units.
Answer:
Câu 2:
Fill in the sequence with the missing number in order to have 3 consecutive natural numbers.
897; ; 899
Câu 3:
Fill in the sequence with the missing number in order to have 3 consecutive natural numbers.
; 87; 88
Câu 4:
How many single digit numbers are there?
Answer: numbers.
Câu 5:
6 is just after of 5 and 5 is just before of 6. What is the product of just after and just before of 10?
Answer:
Câu 6:
Jean has 3014 beads. She has 497 beads less than Gillian. How many beads do they have altogether?
Answer: They have beads altogether.
Câu 7:
There are 56 apples in a basket. of them are green and the rest are red. How many red apples are there?
Answer: There are red apples.
Câu 8:
The perimeter of a square garden is 36m. What is its area?
Answer: Its area is .
Câu 9:
248 boys and 418 girls were divided into groups of 9. How many groups were there altogether?
Answer: groups.
Câu 10:
Mr Junior bought 1 magazine, 1 book and 1 pen. The pen costs 5 dollar, the book costs 31 dollar more than the pen. The magazine costs twice as much as the book. How much did he spend on the three things?
Answer: He spent dollar.
The pages of a book are numbered consecutively from 1 through 120. There are ............ digits are there in this numbering.
one digit: (9-1):1+1=9
two digits: 2x((99-10):1+1)=180
from 100 to 120, we used: 3x((120-100):1+1)=63
So, total is: 9+180+63=252