1/2+3/4+7/8+15/16+...+1023/1024
=1-1/2+1-1/4+1-1/8+1-1/16+...+1-/1024
=10*1-(1/2+1/4+1/8+1/16+...+/1024)
=10-(512/1024+256/1024+128/1024+64/1024+...+/1024)
=10-(1023/1024)
=9又1/1024