The sum of the digits of all 2-digit numbers is .............
The sum of digits of all 2-digit numbers is....................
cách làm:
dãy trên có số các số là:
( 99 - 10) : 1 + 1 = 90
tổng là:
( 99 + 10) x 90 : 2 = 4905
vậy tổng của tất cả số tự nhiên có 2 chữ số là: 4905
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.
the greatest number using digits 4,8 ,0,2,5 only once
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. ...
If B is not divisible by 24 and B is the greatest 5 - digit number that the sum of the sum of all digits is 21 then B = ?
What is the largest 3-digit number that has all of its digits different and is equal to 37 times the sum of its digit ?
What is the sum of all digits of the page numbers of a 76-page book?
How many 5-digit numbers contain all the digits 1, 2, 3, 4 and 5 and have the property that the difference between each pair of adjacent digits is at least 2?
1) Fill the mussing number. A cube has.....vertices
2) Fill the missing number. We're in the....st century
3) Ther are only two 2-digit numbers that are a multiple of 7 and the sum of thetr two digits is 10. Find the sum of these two 2-digit numbers: 70,119,140,21
4) The fourth power of 3 is...
5) Twice the square of 3....
6) The number of ethnic group in Vietnam?
7) The perimeter of 4cm square egde in cm?
1) Fill the mussing number. A cube has \(8\) veres
2) Fill the missing number. We're in the \(21\) st century
3) Ther are only two 2-digit numbers that are a multiple of 7 and the sum of thetr two digits is 10. Find the sum of these two 2-digit numbers: 70,119,140,21 \(70\)
4) The fourth power of 3 is \(64\)
5) Twice the square of 3 \(18\)
6) The number of ethnic group in Vietnam? \(54\)
7) The perimeter of 4cm square egde in cm? \(1\)
Mình cũng đar giải ra như các bạn rồi, chỉ có câu 3) đáp án không phải là 70, mình đã trả lời trên thi toán tiếng Anh rồi. Nhưng dù sao cũng cảm ơn các bạn nhé.
If the sum of first n natural numbers starting with 1 is a 3 digit number with identical digits, find n.
Nếu tổng của n thứ tự tự nhiên đầu tiên bắt đầu bằng 1 là một số 3 chữ số với các chữ số giống nhau, tìm n.
Gọi tổng đó là aaa(aaa thuộc N*)
Ta có:
1+2+3+....+n=aaa
(n+1)x((n-1):1+1) : 2=a x 111
(n+1) x n:2=a x 3 x 37
(n+1) x n=a x 2 x 3 x37
suy ra : (n+1)n chia hết cho 37
suy ra n thuộc {36;37;73;74;....}
Vì 1+2+3+4+...+n=(73+1)73:2=74 x 73: 2=2701(Loại)
suy ra :n<73
suy ra : n thuộc {36;37}
+n=36 Suy ra n+1=37 Suy ra (n+1)n:2=666(Thỏa mãn)
+n=37 Suy ra n+1=38 Suy ra (n+1)n:2=703(Loại)
Vậy n=36