跪求100*1/101+101*1/102+102*1/103……199*1/200=?

1/100*1/101+1/101*1/102+1/102*1/103+……+1/199*1/200
=1/100-1/101+1/101-1/102+1/102-1/103+……+1/199-1/200
=1/100-1/200
=1&