（1/2—1/4+1/6—1/8+1/10+……+1/198—1/200）/1/51+1/52+……1/100=？

1/2-1/4+1/6-1/8+1/10-1/12+…+1/198-1/200
=(1-1/2+1/3-1/4+ ... +1/99-1/100)/2
=[(1+1/2+ ... +1/99+1/100)-2(1/2+1/4+ ... +1/98+1/100)]/2
=[(1+1/2+ ... +1/99+1/100)-(1+1/2+ ... +1/49+1/50)]/2
=(1/51+1/52+1/53+ ... +1/99+1/100)/2

所以原式
=(1/2)(1/51+1/52+1/53+ ... +1/99+1/100)/(1/51+1/52+1/53+…+1/100)
=1/2

答案是1
1/2－1/4＋1/6－1/8+1/10-1/12+……+1/198-1/200)÷（1/51+1/52+1/53+1/54+……1/100）=1