34.5×76.5-345×6.42-123×1.45（简便算法）

34.5×76.5-345×6.42-123×1.45（简便算法）
34.5×76.5-345×6.42-123×1.45（简便算法）

34.5×76.5-345×6.42-123×1.45（简便算法）
34.5×76.5-345×6.42-123×1.45=34.5×(76.5-64.2)-123×1.45 =34.5×12.3-123×1.45 =12.3×(34.5-14.5) =12.3×20 =246