(1-1/2+1/3-1/4.+1/99-1/100 )÷（1/102+1/104+1/106+……+1/200）

(1-1/2+1/3-1/4.+1/99-1/100 )÷（1/102+1/104+1/106+……+1/200）
(1-1/2+1/3-1/4.+1/99-1/100 )÷（1/102+1/104+1/106+……+1/200）

(1-1/2+1/3-1/4.+1/99-1/100 )÷（1/102+1/104+1/106+……+1/200）
(1-1/2+1/3-1/4+...+1/99-1/100)÷(1/102+1/104+..+1/200)
=(1+1/3+..+1/99-1/2-1/4-...-1/100)÷(1/102+1/104+..+1/200)
=[1+1/2+..+1/100-2(1/2+1/4+..+1/100)]÷[1/2(1/51+..+1/100)]
=[1+1/2+..+1/100-(1/1+1/2+..+1/50)]÷[1/2(1/51+..+1/100)]
=(1/51+..+1/100)÷[1/2(1/51+..+1/100)]
=2