1/2-1/4-1/8-1/16-1/32-1/64
=(1-1/2)-(1/2-1/4)-(1/4-1/8)-(1/8-1/16)-(1/16-1/32)-(1/32-1/64)
=1-1/2-1/2+1/4-1/4+1/8-1/8+1/16-1/16+1/32-1/32+1/64
=(1-1/2-1/2)+(1/4-1/4)+(1/8-1/8)+(1/16-1/16)+(1/32-1/32)+1/64
=1/64
1/2-1/4-1/8-1/16-1/32-1/64
=(1-1/2)-(1/2-1/4)-(1/4-1/8)-(1/8-1/16)-(1/16-1/32)-(1/32-1/64)
=1-1/2-1/2+1/4-1/4+1/8-1/8+1/16-1/16+1/32-1/32+1/64
=(1-1/2-1/2)+(1/4-1/4)+(1/8-1/8)+(1/16-1/16)+(1/32-1/32)+1/64
=1/64