问题 解答题
直接写出得数.
3.9×5=3.9×0.5=0.39×5=0.039×0.05=
4.2÷7=4.2÷0.7=0.42÷7=0.42÷0.07=
答案

3.9×5=19.5,3.9×0.5=1.95,0.39×5=1.95,0.039×0.05=0.00195,
4.2÷7=0.6,4.2÷0.7=6,0.42÷7=0.07,0.42÷0.07=6.

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