1/10。
1/5-1/10-1/20-1/40-1/80-1/160-1/320 先算前二个
=1/10-1/20-1/40-1/80-1/160-1/320 再算前二个
=1/20-1/40-1/80-1/160-1/320
=1/40-1/80-1/160-1/320
=1/640
1/10。
1/5-1/10-1/20-1/40-1/80-1/160-1/320 先算前二个
=1/10-1/20-1/40-1/80-1/160-1/320 再算前二个
=1/20-1/40-1/80-1/160-1/320
=1/40-1/80-1/160-1/320
=1/640