2018abc = 2018000 +abc
2018000:321= 6286 rest 194
2018abc =321• 6286 +194+abc
2018abc divizibil cu 321 => 194+abc este divizibil cu 321
194+abc ∈ {1•321, 2•321, 3•321}
194+abc=321 => abc=321-194; abc=127
194+abc=642 => abc=642-194; abc=448
194+abc=963 => abc=963-194; abc=769
2018abc ∈ {2018127, 2018448, 2018769}