abcde*2=edcba =>a为偶数（0,2,4,6,8）,e=2a或者2a+1,aa=0
bcde*2 =edcb0 => 两倍后个位为0=> e=0或者5,四位×2=五为=>e=0或者1 =>e=0
=>bcd0*2=dcb0
同理可以推出d=b=0
=>c00*2=c00
=>c=0
=>a=b=c=d=e=0