... 231 = 230 = 810 910> 810 => 321 > 231 g, 111979 < 111980 = (113 )66 0 = 133 166 0 371320 = (372 )66 0 = 1 369 660 V× 1 369 660 > 133 166 0 => 371320 > 111979 Bµi tËp 7: T×m n ∈ N cho: a) 50 < 2n < 100 b) ... 43.10 + 43 = 430 + 43 = 4373 67 101= 67 67 423 1001 = 423 423 d/ 67 99 = 67 .(100 – 1) = 67 .100 – 67 = 67 00 – 67 = 66 33 998 34 = 34 (100 – 2) = 34.100 – 34.2 = 3400 – 68 = 33 932 Bái 4: Tính nhanh ... a/ Ư (6) , Ư(12), Ư(42) ƯC (6, 12, 42) b/ B (6) , B(12), B(42) BC (6, 12, 42) ĐS: a/ Ư (6) = { 1; 2;3 ;6} Ư(12) = { 1; 2;3; 4 ;6; 12} Ư(42) = { 1; 2;3 ;6; 7;14; 21; 42} ƯC (6, 12, 42) = { 1; 2;3 ;6} b/ B (6) ...