Inverse

[tzungshian]

Print the inverse number. Ex: 2178*4=8712 Write down a program which can satisfy the prerequisite and print out the screen. The answer is: [code]

void inverse2 ()
{
int i,j;
for (i=1000;i<=9999;i++)
for (j=1;j<=9;j++)
if (i*j==inverse (i))
printf("%5d%2d",i,j);

}
[/code]

I can't understand the double for loop.
Can anyone please help me?
Thanks!!!