The numbers in the positive odd number sequence 1,3,5,7... Are arranged into the following triangle number table according to the principle of "top small, bottom large, left small, right large" one 3 5 7 9 11 13 15 17 19 ……… Please judge the number of 2009 in the triangle number table The detailed process is satisfactory

2009 is the 1005th odd number
The last number in line n is: x = ((1 + n) * n / 2) * 2-1
x

RELATED INFORMATIONS

1. Among the odd numbers 1.3.5.697 and 699, how many times does the number 5 appear?
2. Finding the sum of the first n terms of sequence 3,7,11,15.2n-1
3. The observed values (1), (3,5), (7,9,11) (13,15,17,19) were in which group Please write down the calculation or reasoning process
4. 1、153°39'+25°40'38" 2、90°-37°24‘38” 3、25°53’8“×5 4、15°20‘36
5. Simple and convenient operation
6. Simple method of 35 × 35 + 65 × 35
7. 123×123＋123
8. Why is the square of 3:1 equal to 9:3:3:1
9. According to the Pythagorean theorem, the square of a plus the square of B equals the square of C. how to calculate the square of 35 plus 12 equals the square of 50
10. I don't think the formula of Pythagorean theorem is right. 2,3,4cm right triangle 2's Square 4,3's Square 9,4's Square 16, and 4 plus 9 equals 13,16 is greater than 13
11. The set of prime numbers less than 20 is {2.3.5.7.11.13.17.19} prime numbers are prime numbers The set of prime numbers less than 20 in grade one is {2.3.5.7.11.13.17.19}. Prime numbers are prime numbers, and prime numbers cannot be divisible. Why is 2 prime?
12. How to calculate 10 * 7 / 15 =?
13. The numbers 1, 2, 3,... Are written on the blackboard , 2009, arbitrarily erase two numbers a and B, and then rewrite them as the difference between the two numbers, so continue until If there is only one number left, is the last number left odd or even?
14. There are 1, 3 and 5 on the blackboard. There are 1000 numbers in total. Erase two numbers at any time, and then write the sum of the two numbers After how many erasures, there are only two numbers left on the blackboard?
15. Additional questions: write 2000 numbers on the blackboard: 1, 2, 3 , 2000, it is allowed to erase two numbers a and B (a ≥ b) each time and write the three numbers A-B, AB and ab (that is, AB writes twice). After 8000 times of doing so, 10000 numbers are obtained. Q: can these 10000 numbers all be less than 500?
16. Mr. Wang wrote three integers 2,4,8 on the blackboard. Then he erased a number and added a number, which is more than the sum of the two numbers on the blackboard. For example, he erased 4 and added a number 2 + 8 + 1 = 11. At this time, the number on the blackboard is 2,8,11?
17. Write 1, 2,... On the blackboard As long as there are two or more numbers on the blackboard, erase any two of them a and B, and write A-B (where a ≥ b), and ask whether the last one on the blackboard is odd or even
18. The blackboard says 0.01, 0.02, 0.03 Then, 1, these 100 numbers, each time arbitrarily erase two of them a, B, and write 2ab-a-b + 1, and ask what is the number left on the blackboard? Why?
19. There are 2003 numbers on the blackboard. Erase two numbers at any time and write another one______ After that, there is only one number left on the blackboard
20. 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = simple algorithm