2/(2*4)+2/(4*6)+2/(6*8)+........2/(96*98)+2/(98*100)

2/(2*4)+2/(4*6)+2/(6*8)+........2/(96*98)+2/(98*100)
=1/2-1/4+1/4-1/6+..............+1/98-1/100
=1/2-1/100
=49/100