令 M=1/2+3/4+7/8+······+1023/1024 ① 2M=1/1+3/2+7/4+······+1023/512 ②②- ①得M＝1+2/2+4/4+······+512/512 -1023/512 ＝1+ 1+1++······+1 -1023/512=10- 1023/512=4079/512