2005 times brackets 1 times 1 / 2 plus 2 times 1 / 3 plus 3 times 1 / 4, and so on to 2004 times 1 / 2005, please

2005 times brackets 1 times 1 / 2 plus 2 times 1 / 3 plus 3 times 1 / 4, and so on to 2004 times 1 / 2005, please

2005x(1/1x2 +1/2x3+.+1/2004x2005) =2005x(1- 1/2 +1/2 -1/3 +.+1/2004 -1/2005) =2005x(1- 1/2005) =2004