1/2+3/4+7/8+15/16+31/32+63/64+127/128

1/2+3/4+7/8+15/16+31/32+63/64+127/128
1/2+3/4+7/8+15/16+31/32+63/64+127/128

1/2+3/4+7/8+15/16+31/32+63/64+127/128
1/2+3/4+7/8+15/16+31/32+63/64+127/128
=1-1/2+1-1/4+1-1/8+1-1/16+1-1/32+1-3/64+1-1/128
=7-(1/2+1/4+1/8+1/16+1/32+1/64+1/128)
=7-[(1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/128)-1/128]
=7-(1-1/128)
=7-127/128
=6又1/128

六又1/128

原式=7-1/2-1/4-1/8-1/16-1/32-1/64-1/128=7-(64+32+16+8+4+2+1)/128=7-127/128=869/128

1-1/2+1-1/4+1-1/8+1-1/16+1-1/32+1-1/64+1-1/128=7-127/128

1/2+3/4+7/8+15/16+31/32+63/64+127/128
=1-1/2+1-1/4+1-1/8+1-1/16+1-1/32+1-1/64+1-1/128
=7-1/2-1/4-1/8-1/16-1/32-1/64-1/128+1/128-1/128
=7+1-1/128
=7又127/128