6667/Mistake

Source Work

 * The Dictionary
 * $6667$
 * $6667$

Mistake
Not a mistake as such, but:


 * The patterns appearing in $6667^2$, and similarly in $3334^2$ and so on, are examples of a general rule. Any number, of however many digits, will form a pattern when a sufficiently large number of either $3$s, $6$s or $9$s are prefixed to it. Thus, $72^2 = 5184$, $672^2 = 451, 584$ and $6672^2 = 44, 515, 584$ and so on.

is so vaguely worded as to be all but useless.