\(A=1-2-3+4+5-6-7+8+...+99-100-101+102+103\\ =\left(1-2-3+4\right)+\left(5-6-7+8\right)+...+\left(99-100-101+102\right)+103\\ =0+..+0+103\\ =103\)
A = 1 + (-2) + (-3) + 4 + 5 + (-6) + (-7) + 8 + .......... + 99 - 100 - 101 + 102 + 103
A = 1 - 2 - 3 + 4 + 5 - 6 - 7 + 8 + ................ + 99 - 100 - 101 + 102 + 103
A = ( 1 - 2 - 3 + 4 ) + ( 5 - 6 - 7 + 8 ) + ............. + ( 99 - 100 - 101 + 102 ) + 103
A = 0 + 0 + ............. + 0 + 103
A = 0 + 103
A = 103