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)
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
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 .
To assess the number of pages of a book, then we have to use as many digits?
What is the sum of all digits of the page numbers of a 76-page book?
choose any three digits from 1 to 9 to form a 3 - digit number and each digits is chosen only once. how many of these have the sum of all digit equal to 13
Dịch đề: Chọn bất kỳ ba chữ số từ 1 đến 9 để tạo thành một số gồm 3 chữ số và mỗi chữ số chỉ được chọn một lần. Bao nhiêu trong số này có tổng của tất cả các chữ số bằng 13
SOS cíu vời cô anh ra đề này
We use 8 digits 0, 1, 2, 3, 4, 5, 6, 7 to form all 5-digit natural numbers consisting of distinct digits. Find the sum of all numbers that can be formed.
cô bảo hồi cô giỏi toán nhưng đam mê anh
Vãi There are a total of $8\times 7\times 6\times 5\times 4=67,\!200$ ways to form a 5-digit number with distinct digits out of 0, 1, 2, 3, 4, 5, 6, 7. We claim that these can be grouped into $\binom{5}{2}\cdot 2=20$ pairs, where each pair adds up to 7777. The pairs are $(0, 7777), (1, 7776), \ldots, (4, 7773)$ and $(5, 7772), \ldots, (7, 7770)$. Thus, the sum of all the possible numbers is $20\cdot 7777=\boxed{155,540}.$ đó ko biết đúng hay sai nhé
Since we are forming 5-digit numbers, the first digit cannot be 0. Therefore, we have 7 choices for the first digit. After choosing the first digit, we have 7 remaining digits to choose from for the second digit, 6 remaining digits for the third digit, 5 remaining digits for the fourth digit, and 4 remaining digits for the fifth digit. So, the total number of 5-digit numbers that can be formed is 7 * 7 * 6 * 5 * 4 = 5,040. To find the sum of these numbers, we can use the formula for the sum of an arithmetic series: S = (n/2)(a + l), where S is the sum, n is the number of terms, a is the first term, and l is the last term. In this case, the first term is 1,2345 (the smallest 5-digit number that can be formed using the given digits) and the last term is 7,6543 (the largest 5-digit number that can be formed using the given digits). Using the formula, we can calculate the sum as follows: S = (5040/2)(12345 + 76543) S = 2520 * 88888 S = 224,217,600 Therefore, the sum of all numbers that can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7 is 224,217,600. ...
How many four-digit integers greater than 5000 are there for which the thousands digits equals the sum of the other three digits?
Toán tiếng anh,giúp với
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câu 1:16 ; câu 2 : ai mà biết được
