1 + 2 + 3 + 4 + 5 = 15? Do read the previous posts on sequences, we have derived and discussed a formula for summation of natural numbers. In each post on a topic I have assumed that you have read whatever has been discussed prior to that on that topic.
CAT-holics 
I am unable to understand 1,3,6,10 series and how you were able to get summation of (5)=15?
1 + 2 + 3 + 4 + 5 = 15? Do read the previous posts on sequences, we have derived and discussed a formula for summation of natural numbers. In each post on a topic I have assumed that you have read whatever has been discussed prior to that on that topic.
regards
J