5.12x4.5的简便方法怎么算
问题描述：
5.12x4.5的简便方法怎么算
答
方法1：5.12 x 4.5 = 5.12 X (4 + 0.5) = 5.12 X 4 + 5.12 X 0.5 = 20.48 + 2.56 = 23.04
方法2：5.12 x 4.5 = 5.12 X (9 ÷ 2) = (5.12÷2) X 9 = 2.56 X 9 = 2.56 X (10-1) = 2.56 X 10 - 2.56
方法3：5.12 x 4.5 = (5+0.12)X4.5 = 5X4.5 + 0.12X4.5 = (25 - 2.5) + 12 X 9 / 200 = 22.5 + 0.54
方法4：5.12 x 4.5 = (5+0.12)X5 - (5+0.12)X 0.5 = (25 + 0.6) - = 25.6 - 2.56 = 23.04
方法5：5.12 x 4.5 = (5+0.12)X(4 + 0.5) = 20 + 2.5 + 0.48+0.06 = 22.5 + 0.54 = 23.04
方法6：5.12 x 4.5 = (5+0.12)X(5 - 0.5) = 25 - 2.5 + 0.6 - 0.06 = 22.5 + 0.54 = 23.04