1-1/2-1/6-1/12-1/20·······-1/99*100
=1-(1/2+1/6+1/12+1/20·······+1/99*100)
=1-(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+······+1/99-1/100)
=1-(1-1/100)
=1-99/100
=1/100
1-1/2-1/6-1/12-1/20·······-1/99*100
=1-(1/2+1/6+1/12+1/20·······+1/99*100)
=1-(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+······+1/99-1/100)
=1-(1-1/100)
=1-99/100
=1/100