Question

1+3+5+7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37=361
without any calculation how?

Answer 1

The sum of first n odd numbers is the same as

n^2.....


This is the sum of 1st 19 odd terms,

So the sum is equal to

19^2 = 361....