605. Вычислить: 42 × 14; 54 × 16; 43 × 12; 36 × 23; 28 × 34; 24 × 47; 52 × 36; 43 × 64; 25 × 33; 68 × 24; 56 × 32; 72 × 54.

Разложим двузначный множитель на десятки и единицы.

42 × 14 = 42 × (10 + 4) = 420 + 168 = 588.

54 × 16 = 54 × (10 + 6) = 540 + 324 = 864.

43 × 12 = 43 × (10 + 2) = 430 + 86 = 516.

36 × 23 = 36 × (20 + 3) = 720 + 108 = 828.

28 × 34 = 28 × (30 + 4) = 840 + 112 = 952.

24 × 47 = 24 × (40 + 7) = 960 + 168 = 1128.

52 × 36 = 52 × (30 + 6) = 1560 + 312 = 1872.

43 × 64 = 43 × (60 + 4) = 2580 + 172 = 2752.

25 × 33 = 25 × (30 + 3) = 750 + 75 = 825.

68 × 24 = 68 × (20 + 4) = 1360 + 272 = 1632.

56 × 32 = 56 × (30 + 2) = 1680 + 112 = 1792.

72 × 54 = 72 × (50 + 4) = 3600 + 288 = 3888.

Ответ: 588; 864; 516; 828; 952; 1128; 1872; 2752; 825; 1632; 1792; 3888.