精英家教网 > 小学数学 > 题目详情
25×79×4
8×166×25
50×25×4×3
8×(25×15)
(250×72)×4
5×25×13×40×20.
分析:对于连乘的运算,利用了乘法结合律凑整使计算简便.
解答:解:25×79×4
=25×4×79
=100×79
=7900
8×166×25
=8×25×166
=200×166
=33200
50×25×4×3
=(25×4)×(50×3)
=100×150
=15000
8×(25×15)
=8×25×15
=200×15
=3000
(250×72)×4
=250×4×72
=1000×72
=72000
5×25×13×40×20
=(25×40)×(5×20)×13
=1000×100×13
=1300000
点评:如何找准凑整十、整百、整千是本题的关键,然后利用整数乘法的结合律.
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