题目内容
【题目】脱式计算，能简算的要简算。
1.25×0.9×0.8 6.6×3.9+3.9×3.4 42×10.1
5.6×1.25 0.8×0.25×0.4×1.25 9.8÷0.25÷4
【答案】0.9；39；424.2
7；0.1；9.8
【解析】
1.25×0.9×0.8
=(1.25×0.8)×0.9
=1×0.9
=0.9
6.6×3.9+3.9×3.4
=3.9×(6.6+3.4)
=3.9×10
=39
42×10.1
42×(10+0.1)
=42×10+42×0.1
=420+4.2
=424.2
5.6×1.25
=0.8×7×1.25
=(0.8×1.25)×7
=1×7
=7
0.8×0.25×0.4×1.25
=(0.8×1.25)×(0.25×0.4)
=1×0.1
=0.1
9.8÷0.25÷4
=9.8÷(0.25×4)
=9.8÷1
=9.8
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