bai 1,Viet cac phan so thap phan sau duoi dang so thap phan
24 /10=
225 /100 =
6453 / 1000 =
25789 /10000=
bai 2, Mot hinh chua nhat co chieu rong bang 1/3 chieu dai .Neu keo dai moi chieu them 4 cm thi duoc hinh chu nhat moi co chu vi bang 128cm.Tinh chu vi hinh chu nhat ban dau