1、计算:1/1×2+1/2×3+1/3×4+…+1/99×100
	
	  1/1×2+1/2×3+1/3×4+…+1/99×100
	
	  =1-1/2+1/2-1/3+1/3-1/4+…+1/99-1/100
	
	  =1-1/100
	
	  =99/100
	
	  2、计算:1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+1/(4×5×6)+…+1/(21×22×23)
	
	  1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+1/(4×5×6)+…+1/(21×22×23)
	
	  =(1/2)【1/(1×2)-1/(2×3)+1/(2×3)-1/(3×4)+1/(3×4)-1/(4×5)+1/(4×5)-1/(5×6)+…+1/(21×22)-1/(22×23)】
	
	  =(1/2)【1(1×2)-1/(22×23)】
	
	  =(1/2)(126/253)
	
	  =63/253




