原式=1+1/128+2+1/64+4+1/32+8+1/16+16+1/8+32+1/4+64+1/2
=1/128+1/64+1/32+1/16+1/8+1/4+1/2+1+2+4+8+16+32+64
=(1/128+1/64+1/32+1/16+1/8+1/4+1/2)+1+2+4+8+16+32+64
=(1/128+2/128+4/128+8/128+16/128+32/128+64/128)+(1+2+4+8+16+32+64)
=127/128+127
=127又127/128
你可以适当地化简一下过程.