|1/4 - 1/2|+|1/6 - 1/4|+...+|1/2010-1/2008|=1/2 -1/4 + 1/4 - 1/6 + ... + 1/2008 - 1/2010= 1/2 - 1/2010= 1049/2010
1/2-1/2010=1004/2010=502/1005
502/1005