Explanation

The sum of the first 10 natural numbers is:

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55

OR

Formula for natural number= n(n+1)/2

n=10

Now

10(10+1)/2

10(11)/2

5(11)

55