SOLUTION: How do I : Find the sum of the first 400 natural numbers.

Question 83780: How do I :
Find the sum of the first 400 natural numbers.
Found 2 solutions by jim_thompson5910, scott8148:
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Since the first 400 natural numbers is
1,2,3,4,5,6,7...399,400

The sequence is

where n starts at 1 and increments by 1

So to find the sum of the arithmetic sequence from 1 to 400 we can use this formula:

where S is the sum, n is the number of terms (in this case 400), is the first term (in this case 1), and is the last term (in this case 400)

Plug in n=400, and

Add

Multiply

Divide

So the sum of the first 400 natural numbers is 80,200
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
400+1=401 ... 399+2=401 ... 398+3=401 ... this pattern leads to the solution ... 401*200=80200

in general, ((first term)+(last term))*(half the number of terms)

in this case (400+1)*200=80200
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