1-1/2-1/4-1/8-1/16-……-1/1024
=(1-1/2)-1/4-1/8-1/16-……-1/1024
=(1/2-1/4)-1/8-1/16-……-1/1024
=(1/4-1/8)-1/16-……-1/1024
=(1/8-1/16)-……-1/1024
……
=1/512-1/1024
=1/1024
1-1/2-1/4-1/8-1/16-……-1/1024
=(1-1/2)-1/4-1/8-1/16-……-1/1024
=(1/2-1/4)-1/8-1/16-……-1/1024
=(1/4-1/8)-1/16-……-1/1024
=(1/8-1/16)-……-1/1024
……
=1/512-1/1024
=1/1024