Question 20
Find all $n \in \mathbb{N}$ divisible by $11$, such that all numbers that can be obtained from $n$ by an arbitrary rearrangement of its digits are again divisible by $11$.
Macedonian source version, translated in full:
Find all $n \in \mathbb{N}$ divisible by $11$, such that all numbers that can be obtained from $n$ by an arbitrary rearrangement of its digits are again divisible by $11$.
Macedonian source version, translated in full:
Find all $n \in \mathbb{N}$ divisible by $11$, such that all numbers that can be obtained from $n$ by an arbitrary rearrangement of its digits are again divisible by $11$.