Answers

The Brainliest Answer!
2014-10-04T21:55:02+05:30
The formula is n(n+1)/2
for example 1+2+3+4=3+7=10
n=4

4(4+1)/2
=4(5)/2
=20/2
=10
1 5 1
2014-10-04T21:58:22+05:30
Let the no of natural nos be n
so the formula is 
 \frac{n(n+1)}{2}

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