999999999999999999999999999999999999999999999999 x 999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999 x ( 9 x 4 - 6 x 6 )= ?
ĐÚNG , NHANH - TICK !