教教我，急啊~~~~~~~~~~~~~~~~
(3分之1+6分之1+12分之1+24分之1+48分之1+96分之1+192分之1+384分之1)*128=85
( 1/3 + 1/6 + 1/12 + 1/24 + 1/48 + 1/96 + 1/192 + 1/384 ) X 128
= 1/3 X ( 1 + 1/轿老2 + 1/4 + 1/闭含升8 + 1/16 + 1/32 + 1/64 + 1/128 ) X 128
= 1/老蠢3 X ( 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 )
= 1/3 X ( 256 - 1 )
= 1/3 X 255
= 85
计算：(1/3+1/6+1/12+1/24+1/48+1/碰竖96+1/192+1/384)*128
=1/段毕3*128+1/6*128+1/12*128+1/24*128+1/48*128+1/96*128+1/192*128+1/384*128
=1/3*128+1/3*64+1/3*32+1/3*16+1/3*8+1/3*4+1/3*2+1/握吵芹3*1
=1/3(128+64+32+16+8+4+2+1)
=1/3*255
=85