Question

What is the sum of the arithmetic series of odd numbers below 1+3+5+...+27

Answer 1

196

Explanation:

1+2+3+4+......+25+26+27 = (1+27) + (3+25) + (5+23)+(7+21) + (9+19) + (11+17) + (13+15)

= 28 x 7 = 196

It's like area of trapezoid of bases: 1, 27 and height of 14