1-(1/2+1/4+1/8+1/16+1/32+1/64+1/128)=1-(1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/128-1/128)=1-(1/2+1/4+1/8+1/16+1/32+1/64+1/64-1/128)……=1-(1/2+1/2-1/128)=1-(1-1/128)=1/128