`=1/2 xx 2/3 xx 3/4 xx...xx 2002/2003 xx 2003/2004`
`=1/2004`
`(1-1/2)xx(1-1/3)xx.......xx(1-1/2003)xx(1-1/2004)`
`=(2/2-1/2)xx(3/3-1/3)xx....xx(2003/2003 - 1/2003)xx(2004/2004-1/2004)`
`=1/2 xx 2/3 xx ..... xx 2002/2003 xx 2003/2004`
`=(1xx2xx.....xx2002)/(2xx3xx.....xx2004)`
`=1/2004`