(1-1/2004)(1-1/2003)(1-2002)...(1-1/3)(1-1/2)=要有计算过程

(1-1/2004)(1-1/2003)(1-2002)...(1-1/3)(1-1/2)=
要有计算过程

(1-1/2004)(1-1/2003)(1-2002)...(1-1/3)(1-1/2)
=(2003/2004)(2002/2003)(2001/2002)...(2/3)(1/2)
中间约分约掉了
=1/2004