Latest IES EC Aptitude Question SOLUTION: Below given are two formulae for long summation. 1) 1 + 2 + 3 + 4 + ................ + n = n(n+1)/2 2) 1^2 + 2^2 + 3^2 + 4^2 + ........ + n^2 = 1/6 n(n+1)(2n+1) The value of (1% o