Anyone can help me with this problem?
Find the integers that in decimal radix the tens and units of their square are equals.
$a = 2p − 1, b = 2p + 1, c = 2p + 3.$ Find $p$ that $a^2 + b^2 + c^2$ is equal to a number of four digits which are all equals.
Prove that in $11211$ in radix $b \ge 3 $ is never prime.
For the $3$ I find that if $b$ is a multiple of $3$ than the number is pair and if not the number is a multiple of $3$ but I would like to know if there is another way.