A more difficult mathematical problem, a 6-digit number, each number on the left is always greater than or equal to the number on the right. How many such 6-digit numbers For example, 99999654321665554, 100000, But 120000 doesn't work because two is greater than one

A more difficult mathematical problem, a 6-digit number, each number on the left is always greater than or equal to the number on the right. How many such 6-digit numbers For example, 99999654321665554, 100000, But 120000 doesn't work because two is greater than one

15 * 14 * 13 * 12 * 11 * 10 / (6 * 5 * 4 * 3 * 2 * 1) - 1 = 5004 species
Joke read a 72 story book, the first day read 4 / 9 of the book, the second day read the remaining 2 / 5, the second day read how many pages?
Sixteen
Primary school sixth grade mathematics problem with simple calculation, the following question 2 / 9-7 / 16 * 2 / 9 which Pro will ah online and so on
2/9-7/16*2/9
=2/9*(1-7/16)
=2/9*9/16
=1/8
2/9－7/16×2/9
＝1×2/9－7/16×2/9
＝（1－7/16）×2/9
＝9/16×2/9
＝1/8
2/9-7/16*2/9 = 2/9(1-7/16)=2/9*9/16=1/8
2/9-7/16*2/9
=2/9(1-7/16)
=（2/9）*（9/16）
=2/16
=1/8
2/9－7/16×2/9
＝1×2/9－7/16×2/9
＝（1－7/16）×2/9
＝9/16×2/9
＝1/8
This is good
The quotient of three digits divided by one digit is at most three digits and at least two digits, right
correct
On the first day of reading a story book, I read 2 / 9 of the whole book, which is 50 pages less than half of the whole book. How many pages does the story book have?
Suppose there are x pages in the book
2 / 9 (two out of nine) x + 50 = x / 2
X = 180
A: the book has 180 pages
(17,16),(14,10),(13,4)( ,2 )
Sure enough, it's 18
Eighteen
(18,2)
The difference between two numbers is the square of n
(18, 2) 17-16 = 1 is the square of 1, 14-10 = 4 is the square of 2, 13-4 = 9 is the square of 3, 18-2 = 16 is the square of 4
Eighteen
A four digit number minus the sum of its digits is equal to 19a9?
A four digit number minus the sum of its digits, the rest must be divisible by 9
So 9|19a9
so a=8
A=3
No solution is necessary
Xiao Ming read 50 pages of a story book on the first day, which is 2 / 5 of the story book. How many pages is the story book?
50 △ 2 / 5 = 125 (page)
The second power of 2 + the second power of 4 + the second power of 6 + +To the power of 2 =?
Let n be the number one
The second power of 2 + the second power of 4 + the second power of 6 + +The second power of 50
=(2n) & n from 1 to 25
=4×﹙1²+2²+3³.+25²﹚
twenty-two thousand and one hundred
2^2+4^2+…… +50^2=4*(1+2^2+…… +25 ^ 2) = 4 * (25 * 51 * 26) / 6 = 22100. Please add a few more addends. thank you!!
The order of numbers 435 and 534 is opposite. We call them inverse ordinals. Now there is a pair of inverse ordinals whose product is equal to 92565. These two numbers are ()
Decompose the prime factor, 92565 = 3 * 3 * 5 * 11 * 11 * 17, and use these factors to form two numbers that meet the conditions. There is a 5 in the factor, but there is no even number, so there must be a number that ends with 5, and the other number begins with 5. According to these clues, we can get 561 and 165