题目内容
【题目】脱式计算
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].
【答案】1.2;8.75;54.2;3.6;2.4.
【解析】
试题分析:①把3.2分解成8×0.4再根据乘法结合律进行计算;
②先算除法,再多左到右依次进行计算;
③根据乘法分配律进行计算;
④先算括号里面的,再根据乘法交换律和结合律进行计算;
⑤先算小括号里面的,再算中括号里面的,最后算括号外面的.
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.
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