do cac bn cau nay nhe: (999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999x99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999+ 8888888888888888888888888888888888888888+98888888888888888975875684645)x0=may
bat cu so nao nhan voi 0 cung bang 0
ừ toán lớp 1 mà người lớn giải không được