64.7—3.89+13.69,怎样使计算简便急救
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64.7—3.89+13.69,怎样使计算简便急救64.7—3.89+13.69,怎样使计算简便急救64.7—3.89+13.69,怎样使计算简便急救64.7—3.89+13.69=64.5+0.2+
64.7—3.89+13.69,怎样使计算简便急救
64.7—3.89+13.69,怎样使计算简便
急救
64.7—3.89+13.69,怎样使计算简便急救
64.7—3.89+13.69
=64.5+0.2+13.69-3.89
=64.5+(13.89-3.89)
=64.5+10
=74.5
原式=64-3+13+(0.7-0.89+0.69)
=74+0.5=74.5
65-4+14-0.3+0.11-0.31=
75-0.5=74.5
64.7—3.89+13.69
=64-3+13+0.7-0.89+0.69
=74+0.7-0.2
=74+0.5
=74.5
64.7-3.89+13.69
=64.7-3.89+13.89-0.2
=64.7+10-0.2
=74.5
(思路:因为3.89和13.69的差和10比较接近,故在这里吧-3.89+13.69看成+10,再减去多加的0.2)