1/4+1/8+1/16+1/32+1/64+1/128+1/512
= 1/512 × (128 + 64 + 32 + 16 + 8 + 4 + 1)
= 253/512
1/4+1/8+1/16+1/32+1/64+1/128+1/256+1/512
= 1/512 × (128 + 64 + 32 + 16 + 8 + 4 + 2 + 1)
= 255/512
你看是哪一个?