Question

19．简便计算 6.4×41.2+66.2×3.6．

Answer 1

分析 把66.2×3.6改写成（41.2+25）×3.6，然后再利用乘法分配律和结合律进行计算．

解答 解：6.4×41.2+66.2×3.6
=6.4×41.2+（41.2+25）×3.6
=6.4×41.2+41.2×3.6+25×3.6
=41.2×（6.4+3.6）+25×（4×0.9）
=41.2×10+（25×4）×0.9
=412+100×0.9
=412+90
=502

点评 考查学生对乘法分配律和结合律的掌握情况．