( 1 - 1/99) x ( 1 - 1/100) x...(1 - 1/2006)

* Hướng dẫn giải

(1-1/99).(1-1/100)....(1-1/2006) =(99/99-1/99).(100/100-1/100)....(2006/2006-1/2006) = (98/99).(99/100)...(2005/2006) =98/2006=..