Repeated Concatenation
Number Theory
Level
3
Concatenating four copies of 23 produces \(23 || 23 || 23 || 23 = 23232323.\)
Positive integer \(n\) is of unknown digit length.
What is the minimum number of copies of \(n\) that you need to concatenate to ensure the result is a multiple of 11?
by
Stephen Mellor