用简便方法计算下面各题
(1)
(2)
(3)4.3×11.8+86×0.91???????????????????????????
(4)7.46×36+74.6×6.4.
网友回答
解:(1),
=(+)+(+),
=10+8,
=18;
(2)×+×,
=()×,
=×,
=;
(3)4.3×11.8+86×0.91,
=43×1.18+43×1.82,
=43×(1.18+1.82),
=43×3,
=129;
(4)7.46×36+74.6×6.4,
=74.6×3.6+74.6×6.4,
=74.6×(3.6+6.4),
=74.6×10,
=746.
解析分析:(1)可以运用加法结合律和加法交换律简算;
(2)运用乘法分配律简算;
(3)、(4)变形后再运用乘法分配律简算.
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.