I'd like to know how much it is to add 1 / 200 to 199 / 200

I'd like to know how much it is to add 1 / 200 to 199 / 200

(1+2+…… +198+199)/200
=[(1+199)+(2+198)+…… +(99+101)+100]/200
=(200*99+100)/200
=99.5
The landlord is very boring