解题思路:(1)运用乘法分配律简算;
(2)运用乘法结合律简算;
(3)、(4)根据先算乘除,再算加减,有括号的先算括号里面的运算顺序计算.
(1)7.05×23.7+7.05×76.3,
=7.05×(23.7+76.3),
=7.05×100,
=705;
(2)0.125×3.2×2.5,
=0.125×8×0.4×2.5,
=1×1,
=1;
(3)(12+23.1÷0.75)×0.4-5.12,
=(12+30.8)×0.4-5.12,
=42.8×0.4-5.12,
=17.12-5.12,
=12;
(4)1.6×[(12-7.2)÷(0.84÷2.1)],
=1.6×[4.8÷0.4],
=1.6×12,
=19.2.
点评:
本题考点: 小数四则混合运算.
考点点评: 运算定律是常用的简便运算的方法,要熟练掌握,灵活运用;有些常用的乘法的积要记住,如:25×4=100,125×8=1000等.