1/1*2=(2-1)/1*2=2/1*2-1/1*2=1-1/2
1/2*3=(3-2)/2*3=3/2*3-2/2*3=1/2-1/3
后面以此类推
所以原式=1-1/2+1/2-1/3+1/3-1/4+……+1/2005-1/2006
=1-1/2006
=2005/2006
1/1*2=(2-1)/1*2=2/1*2-1/1*2=1-1/2
1/2*3=(3-2)/2*3=3/2*3-2/2*3=1/2-1/3
后面以此类推
所以原式=1-1/2+1/2-1/3+1/3-1/4+……+1/2005-1/2006
=1-1/2006
=2005/2006