原式=1-1/2-1/4-1/8-1/16-1/32 =1/2-(1/2-1/4)-(1/4-1/8)-(1/8-1/16)-(1/16-1/32) =1/2-1/2+1/4-1/4+1/8-1/8+1/16-1/16+1/32 =1/32