1分之【1乘以2】+1/【2乘以3】+1/【3乘以4】+1/【4乘以5】+……+1/【2005乘以2006】
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+……+1/2004-1/2005+1/2005-1/2006
=1-1/2006
=2005/2006