#include <stdio.h>

#define SIX    1 + 5
#define NINE   8 + 1

int main()
{
printf( "The meaning of life: %d\n", SIX * NINE );
return( 0 );
}

Please note: The output of this program would in fact be:

The meaning of life: 42

The source of this was discovered from a link posted in a journal entry in the community.