Find the law: 0, - 1, + 4, - 5, + 8, - 9, + 12, - 13 What is the number 2010? …… Write the process of calculating the answer

Find the law: 0, - 1, + 4, - 5, + 8, - 9, + 12, - 13 What is the number 2010? …… Write the process of calculating the answer

--4017

Look for the rule 2 1 4 3 6 9 8 7 27 10 () What's the rule in ()?

It's true that there is an extra 7. If you remove this 7, there will be a rule
The odd digits are 2,4,6,8 arithmetic sequences
Even bits are the nth power of 1,3,9,27,813
So it should be filled in 81

Find the rule 1, - 2,3, - 4,5, - 6,7, - 8,9, - 10 The number of regularly arranged columns: 2,4,6,8,10,12... Each term can be expressed by the formula 2n (n is a positive integer). The number of regularly arranged columns: 1, - 2,3, - 4,5, - 6,7, - 8 (1) What formula do you think can be used to express each term?

This. An = (- 1) to the power of (n + 1) * n

According to the rule of "123 456 789 101 112...", write out a number of 2007 digits. What is the number on the billion digits of this number?

The 100 million bits of 2007 digits are the 9th from the bottom and 1999 from the ordinal. It is easy to obtain the result of 7 by using the Pascal program
program ygb;
var s,s2:string;
var i,n,m:integer;
begin
n:=0;
i:=1;
while true do
begin
str(i,s2);
s:=s+s2;
i:=i+1;
if length(s)>107 then
if n>=1900 then break
else begin
{1}writeln(copy(s,1,100));
delete(s,1,100);
n:=n+100;
end;
end;
{2}writeln(copy(s,1,2007-n));
writeln(s[1999-n]);
end.
Other languages can get the results in a similar way. The annotated {1} and {2} statements output this complete 2007 bit data. If the annotation is omitted, it will not be output. The last statement will output the result

“123 456 789 101 112……” This rule writes out a number of 2007 digits, and the number on the billion digits is

The number of 100 million digits in this number is 700 million digits, that is, the 9th digit from the bottom of 2007 digits. We must know how many numbers are written in this string. We may as well add 0 before one digit to 9 and two digit number from 10 to 99 to make up three digit, and add 9 * 2 + 90 * 1 = 108 digit in total

12345678910112. The number before the 100th comma is ()

There are 300 digits before a hundred commas
1: 9 9 digits
2: 9 + 90 × 2 = 189, 111 / 3 = 37;
3: It takes 37 three digits to start at 100, and that's 136
The numbers before 100 commas are all on the top, and the last one is 136!

4, 3, 6, 9, 8, 27, 10, find the law

Arithmetic sequence with tolerance of 2 for 4,6,8,10,12
3,9,27,81 ratio sequence with common ratio of 3
So 12, 81 in the space

1+3+5+7+9+11+13+15+17+19+21+23+25+27+29+…… +101

1+3+5+7+9+11+13+15+17+19+21+23+25+27+29+…… +101
=（1 + 101）× 51÷2
=2601

Observe the following numbers in a certain order: 1, - 2,4, - 8 Then the fifth number is_____ The 100th number is_____ .

（-1)^(n-1)*2^(n-1)
-To the nth power of 1 times the N-1 power of 2
The fifth number is 16
The 100th number - 2 ^ 99

The number of columns arranged according to the rule: 2,5,9,14,27 ····. What is the 2009 number of this series of numbers?

5-2 = 3,9-5 = 4,14-9 = 5. And so on, that is: 2 + 3 + 4 + 5 + 6 + 7 + 8 +... + 2008 (because 2 is not included)
We have to use the arithmetic sequence. 2008 + 2 is an array, there are 2009 numbers in total, that is (2008 + 2) × 2009 △ 2 = 2019045
A: the 2009 number in this series is 2019045