原题好像不对哦,是不是这样:
1/(1*2)+1/(2*3)+1/(3*4)+.+1/(2011*2012)
=(1/1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/2011-1/2012)
=1-1/2012
=2011/2012