The eleventh number is ()

The eleventh number is ()

1/3,3/6,5/9,7/12,9/15,11/18
(2n-1)/3n
The eleventh number is 21 / 33 = 7 / 11

What's the answer when the nth number is 2 / 7 / 8-16 / 9

2 / 3 → 2 / 3 → - 1 ^ (1 + 1) * 2 ^ 1 / (2 * 1 + 1)
-4 / 5 → - 4 / 5 → - 1 ^ (2 + 1) * 2 ^ 2 / (2 * 2 + 1)
8 / 7 → - 1 ^ (3 + 1) * 2 ^ 3 / (2 * 3 + 1)
-16 out of 9 → - 16 / 9 → - 1 ^ (4 + 1) * 2 ^ 4 / (2 * 4 + 1)
The nth → - 1 ^ (n + 1) * 2 ^ n / (2 * n + 1)

1 3 5 7 9 11 13 15 17 what is the n th number in this column

2n-1

1,3,5,7,9,11…… The nth in this column? 1,3,5,7,9,11…… What's the nth number in this series? What's 507 in this series?

The nth is 2N-1
2n-1=507
2n=508
n=254
507 is 254 in this series

According to the rule, the order of the number of columns is: - 1,3, - 5,7, - 9,11 , According to this rule, the 20th number in this column is (); the nth number is ()

Thirty-nine
(-1)^n*(2n-1)

There are 2011 numbers, press 12345432123454321 What is the 2011 number?

"12345432" 8 number cycles:
2011/8=251…… Three
So the number of 2011 is 3

How many digits 5 are included in 2011 natural numbers? How many numbers are there in total

There is one in one digit, 19 in two digits, two in 55, 20 in 100-200 and 100 + 20 = 120 in 500-600
100-1000 has 20 * 9 + 100 = 2801000-2000 has 1 + 19 + 280 = 300
Therefore, there are 300 * 2 + 1 = 601
That's the hope for you

There is a column number: 1, 2, 1, - 1 The law is: from the second number, each number is the sum of the two numbers before and after it. According to this law, the 2011 number is______ .

The first number is 1;
The second number is 2;
The third number is 1;
The fourth number is - 1;
The fifth number is - 2;
The sixth number is - 1;
The seventh number is 1;
The eighth number is 2 ,
∵2011÷6=335… 1，
The number of 2011 is 1
So the answer is: 1

There is a column of numbers: 120062005, 120042003, 1 From the third number, each number is the difference between the large number minus the decimal of the first two numbers

There are 2006 in total
In 120062005, this column is a group of three numbers
2006/3=668.2
So there are 668 groups, followed by two, 1 and X
It is determined that there are 668 1 in the former 668 group, and the remaining 668 * 2 = 1336 arithmetic series with the first term of 2006 and the tolerance of - 1, then the 1336th number = 2006-1336 + 1 = 671,
So the sequence can be written as
1,2006,2005,1,2004,2003,1,…… ,1,672,671,1,670
So Sn = (668 * 1 + 1) + (2006 + 670) * (1336 + 1) / 2
=1789575

27.2.9.4.3.8.1 find rules from these numbers

The odd number is: 27,9,3,1 ------ (3 m3, 3 2, 3 ^ 1,3 ^ 0, --)
Even number of bits: 2,4,8, - -------- (2,2?, 2?, - - -)