Question

【題目】脫式計(jì)算

①0.125×3.2×0.5

②8.25+56÷32﹣1.25

③5.42×7.6+3.4×5.42﹣5.42

④2.5×（6.2﹣2.6）×0.4

⑤15.6÷[（20.75﹣4.5）×0.4]．

Answer 1

【答案】1.2；8.75；54.2；3.6；2.4．

【解析】

試題分析：①把3.2分解成8×0.4再根據(jù)乘法結(jié)合律進(jìn)行計(jì)算；

②先算除法，再多左到右依次進(jìn)行計(jì)算；

③根據(jù)乘法分配律進(jìn)行計(jì)算；

④先算括號(hào)里面的，再根據(jù)乘法交換律和結(jié)合律進(jìn)行計(jì)算；

⑤先算小括號(hào)里面的，再算中括號(hào)里面的，最后算括號(hào)外面的．

解答：解：①0.125×3.2×0.5

=0.125×8×0.4×0.5

=（0.125×8）×（0.4×0.5）

=1×0.2

=0.2；

②8.25+56÷32﹣1.25

=8.25+1.75﹣1.25

=10﹣1.25

=8.75；

③5.42×7.6+3.4×5.42﹣5.42

=5.42×（7.6+3.4﹣1）

=5.42×10

=54.2；

④2.5×（6.2﹣2.6）×0.4

=2.5×3.6×0.4

=2.5×0.4×3.6

=1×3.6

=3.6；

⑤15.6÷[（20.75﹣4.5）×0.4]

=15.6÷[16.25×0.4]

=15.6÷6.5

=2.4．