这些数的规律是后一个数的两倍就是他前一个数,如1/1024+1/1024=1/512,1/512+1/512=1/256,
1/8+1/8=1/4,1/4+1/4=1/2
所以可以先多加一个1/1024,最后再减1/1024
1/2+1/4+1/8+……+1/512+1/1024
=(1/2+1/4+1/8+……+1/512+1/1024+1/1024)-1/1024
=(1/2+1/4+1/8+1/512+1/512)-1/1024
=1/2+1/2-1/1024=1-1/1024=1023/1024