先用你的例子说明:1-(1∕2+1∕4+1∕8)=1-1∕2-1∕4-1∕8=1∕2-1∕4-1∕8=1∕4-1∕8=1∕81∕2+1∕4+1∕8=1-1/8=7/81/2+1/4+1/8+...+1/2^n=1-1/2^n=(2^n-1)/2^n从1/2加到1/16=15/16从1/2加到1/32=31/32从1/2加到1/64=63/64.......