Vì c*5 chia hết cho 5 nên d chia hết cho 5 mà d khác 0 nên d=5.
Vì a*5 nhỏ hơn hoặc bằng d mà d=5 nên a<2 mà a khác 0 nên a=1.
Ta có:
1bc*5=515
1bc=515/5
1bc=103
Vậy abc=103.
103 mình cas 99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999%
