[TEX]S=1^2+2^2+3^2+......+100^2[/TEX]
[TEX]=1.(2-1)+2.(3-1)+3.(4-1)+.....+100.(101-1)[/TEX]
[TEX]=1.2-1+2.3-2+3.4-3+.........100.101-100[/TEX]
[TEX]=1.2+2.3+3.4+.....+100.101-(1+2+3+4+...+100)[/TEX]
[TEX]=\frac{100.101.102}{3}[/TEX]-[TEX]\frac{100.(100+1)}{2}[/TEX]
[TEX]=343400-5050[/TEX]
[TEX]=338350[/TEX]