1 2 x 3 4 x 9 10 July 8, 2019 16 32 64 128 1 3 4 x 9 1 2 x 10 lvl 1.9 e Tìm x biết x 1 x 2 x 3 x 4 x 9 x 10 2015 1 + 2 + 3 + 4 = 10
