计算（1-1/2）的绝对值+（1/2-1/3）绝对值+（1/3-1/4）绝对值+...+（1/2006-1/2007）绝

|1-1/2|+|1/2-1/3|+|1/3-1/4|+…+|1/2006-1/2007|
=1-1/2+1/2-1/3+1/3-1/4+…+1/2006-1/2007
=1-1/2007
=2006/2007