(1)15×(2)1200-840÷24(3)3+1.5÷2.5÷4(4)8-4.4×0.25(5)(6)()×12÷.
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解:(1)15×
=15××,
=18×,
=14;
(2)1200-840÷24
=1200-35,
=1165;
(3)3+1.5÷2.5÷4
=3+1.5÷(2.5×4),
=3+1.5÷10,
=3+0.15,
=3.15;
(4)8-4.4×0.25
=8-1.1×(4×0.25),
=8-1.1×1,
=8-1.1,
=6.9;
(5)
=-,
=;
(6)()×12÷.
=(×12-×12)×,
=(9-4)×,
=5×,
=6.
解析分析:(1)可根据乘法交换律进行计算;
(2)(5)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
(3)可根据一个数除以两个数,等于除以这两个的积的除法性质计算;
(4)可将4.4拆分为1.1×4后根据乘法结合律计算;
(6)可根据乘法分配律计算.
点评:完成本题要注意分析式中数据,然后先择合适的方法进行计算.