A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
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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
From 1 to 9 have 9 numbers with 1 digit. So there are 9 digits.
From 10 to 99 have 90 numbers with 2 digits. So there are: 90 x 2 = 180 ( digits )
From 100 to 250 have 151 numbers with 3 digits. So there are: 151 x 3 = 453 ( digits )
The book needs the number of digits:
9 + 180 + 453 = 642 ( digits )
Answer: 642 ditgits
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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...
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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
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?
Từ trang 1 đến trang 9 dùng 9 chữ số . Từ trang 10 đến trang 35 dùng : ( 35 - 10 ) : 1 + 1 x 2 = 52 ( chữ số ) . Quyển sách dày : 52 + 9 = 61 ( trang )
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61 trang . bạn có thể tham khảo bài trong câu hỏi tương tự .
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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
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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?
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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
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The pages of a book are numbered consecutively from 1 through 120. There are ............ digits are there in this numbering.
dịch: một quyển sách đánh số trang liên tiếp tù 1 đến 120.Có ..... chữ số trong quyển sách này?
giải
từ 1 đến 9 có: 9 chữ số
từ 10 đến 99 có :90 số x 2=180 chữ số
từ 100 đến 120 có :21 số x 3 =63 chữ số
có tất cả là :9+ 180+ 63= 252 chữ số
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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 ?
Combinatorics21. 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. H...
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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 ~
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 ~
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