设abcde=x,则有abcdef=10x+f,fabcde=100000f+x
所以(10x+f)*f=100000f+x
x=(100000f-f^2)/(10f-1)=10000+(10000-f^2)/(10f-1)=10000+(100+f)(100-f)/(10f-1)
由于0<=f<=9,f为整数 并且x为整数,所以(100+f)(100-f)/(10f-1)为整数,且由于x>=10000,
所以(100+f)(100-f)/(10f-1)>=0,
把f=0到9依次带进去验证一下 有如下的解
x=11111,f=1,abcdef=111111
x=10256,f=4,abcdef=102564