1/2+1/4=3/4
1/2+1/4+1/8=7/8
1/2+1/4+1/8+1/16=15/16
...
1/2+1/4+1/8+1/16+1/32+1/62+1/128+1/256=255/256Thank you !别客气，谢谢采纳