1又2分之1+2又4分之1+3又8分之1一直加到8又256分1
=1+1/2+2+/4+3+1/8+.+8+1/256
=1+2+3+.+8 + 1/2 +1/4+1/8+...+1/256
=(1+2+3+.+8 )+ (1/2 +1/4+1/8+...+1/256)
=(1+8)*8/2 +(1-1/2+1/4+1/8+...+1/256)
=36+1-(1/2-1/4-1/8-...-1/256)
=36+1-1/256
=36又256分之255