Question 200
Find out which significant four-digit numbers, $\overline{a b c d}$ (with $a \neq 0$), are the same as $\overline{a b}^{2} + \overline{c d}^{2} - \overline{c d}$. Note: The $\overline{a b}$ notation represents, in this problem, the number that $a$ has tens and $b$ units; In this case you have that $a, b \in \{0,1,2,3,4,5,6,7,8,9\}$.