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计算:(1)1.25×1.25×┄×1.25×0.8×0.8×┄×0.812个1.25 13个0.8(2)31.6×7.

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/11/01 07:02:38
计算:
(1)1.25×1.25×┄×1.25×0.8×0.8×┄×0.8
12个1.25 13个0.8
(2)31.6×7.6+184×0.77
(3)(6+43+473+5414+43444) ×2.5
应该是有一种适合孩子的简单算法吧?
是的,有简便算法.
(1)1.25×1.25×┄×1.25×0.8×0.8×┄×0.8
= (1.25×0.8)×┄×(1.25×0.8)×0.8
12个(1.25×0.8) 1个0.8
= 1×┄×1×0.8
=0.8
(2)31.6×7.6+184×0.77
= 316×0.76 + 184×(0.76+0.01)
= (316+184)×0.76 + 184×0.01
= 500×0.76 + 1.84
= 380 + 1.84
= 381.84
(3)(6+43+473+5414+43444) ×2.5
= [(6+5414)+(43+473)+43444]×2.5
= (5420+516+43444)×2.5
= (5420/4+516/4+43444/4)×4×2.5
= (1355+129+10861)×10
= 123450
最后这题我没有想到特别简便的方法,基本上是硬算了.