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The sum of the odd numbers in an even-ending sequence is 2/5 of the total sum. The sum of an arithmetic sequence is
Sn = n(a1 + an)/2
Sn = n(a1 + an)/5
Sn = 400(1+400)/5
Sn = 32080
* * * * *
Very convincing but totally incorrect!
Simply try it out for the first 2 consecutive odd numbers:
1 + 3 = 4
1 + 2 + 3 = 6 but 4 is not 2/5 of 6!
The correct answer:
The nth odd number is 2n - 1
The sum of the 1st and 400th odd numbers is 2*1-1 + 2*400-1 = 2*401 - 2 = 2*400 = 800
The sum of the 2nd and 399th odd numbers is 2*2-1 + 2*399-1 = 2*401 - 2 = 2*400 = 800
there are 200 such pair so the grand total is 800*200 = 160,000
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What is the sum of the first 20 consecutive odd numbers?
The answer is 20*20 = 400
What is the first 30 sum consecutive odd numbers?
The sum of the first 30 consecutive odd numbers is 900.
What is the sum of the first 350 consecutive odd numbers?
The sum of the first 350 consecutive odd numbers is 122,500.
What is the sum of the first 30 consecutive odd numbers?
The sum of the first 30 consecutive odd numbers is 900.
What is the sum of the first 900 consecutive odd numbers?
The sum of the first 900 consecutive odd numbers is 810,000.
What is the sum of the first 20 consecutive odd numbers?
The answer is 20*20 = 400
What is the sum of the first 60 consecutive odd numbers?
The sum of the first 60 consecutive odd numbers is 3,600.
What the sum of the first 60 consecutive odd numbers?
The sum of the first 60 consecutive odd numbers is 3,600.
What is the sum of the first 50 consecutive odd numbers?
the sum of first 50 consecutive odd numbers is 9801
What is the sum of the first 600 consecutive odd numbers?
The sum of the first 600 consecutive odd numbers is 360,000.
What is the first 30 sum consecutive odd numbers?
The sum of the first 30 consecutive odd numbers is 900.
What is the sum of the first 350 consecutive odd numbers?
The sum of the first 350 consecutive odd numbers is 122,500.
What is the sum of the first 30 consecutive odd numbers?
The sum of the first 30 consecutive odd numbers is 900.
What is the sum of the first 900 consecutive odd numbers?
The sum of the first 900 consecutive odd numbers is 810,000.
What is the sum of the first 250 consecutive odd numbers?
The sum of the first 250 consecutive odd numbers is 250 squared or 62,500.
What is the sum first 450 consecutive odd numbers?
The sum of the first 450 consecutive odd numbers is 450 squared or 202,500.
What is the sum of the first 1300 consecutive odd numbers?
The sum of the first 1,300 consecutive odd numbers is 1,300 squared or 1,690,000.
