A repunit of length k is a number containing k ones (1, 11, 111...).
R(k) is defined to be the repunit of length k.
A(n) is the least value of k such that R(k) is divisble by n (assuming gcd(n, 10) = 1).
Reading online, several articles claim that A(n) < n, but no explanation is given (and that's why I'm assuming I'm missing something obvious...), and I don't understand how that inequality came to be. An explanation on why that inequality holds would be very appreciated.