Răspuns :
712x...4=
7120...4=7120/4=1780
712x...(... inseamna divizibil)
7124...4=7124/4=1781
7128..4=7128/4=1782
{7120,7124,7128}...4
7120...4=7120/4=1780
712x...(... inseamna divizibil)
7124...4=7124/4=1781
7128..4=7128/4=1782
{7120,7124,7128}...4