User-defined Sorting:

Original Order:

0 => 109
1 => 67
2 => 38
3 => 12
4 => 90
5 => 65
6 => 42

Numerical Sort Order:

0 => 12
1 => 38
2 => 42
3 => 65
4 => 67
5 => 90
6 => 109

Modulus 19 Sort Order:

0 => 38 ≡ 0 (Mod 19)
1 => 42 ≡ 4 (Mod 19)
2 => 65 ≡ 8 (Mod 19)
3 => 67 ≡ 10 (Mod 19)
4 => 12 ≡ 12 (Mod 19)
5 => 90 ≡ 14 (Mod 19)
6 => 109 ≡ 14 (Mod 19)