Question

【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

Answer 1

【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