题目内容
脱式计算,能简算的要简算
(1)745×2.4+6.2×225+2.4
(2)[(0.8-415 )÷1313+1.76]×(0.75÷634 )
(1)745×2.4+6.2×225+2.4
(2)[(0.8-415 )÷1313+1.76]×(0.75÷634 )
分析:本题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,有括号的要选算括号里面的.
(2)中0.8-415不够减,结果为负数,用后边的415减0.8,然后在结果后边加上“-”号即可.由于式中数值较大,而且不能约分,因此式中小数做分子时不用化为整数,直接用小数作分子即可,1.76化为分数时,直接用1313作为分母即可.
(2)中0.8-415不够减,结果为负数,用后边的415减0.8,然后在结果后边加上“-”号即可.由于式中数值较大,而且不能约分,因此式中小数做分子时不用化为整数,直接用小数作分子即可,1.76化为分数时,直接用1313作为分母即可.
解答:解:(1)745×2.4+6.2×225+2.4,
=1788+1395+2.4,
=3185.4;
(2)[(0.8-415)÷1313+1.76]×(0.75÷634),
=[(-414.2)÷1313+1.76]×
,
=[-
+
]×
,
=
×
,
=
.
=1788+1395+2.4,
=3185.4;
(2)[(0.8-415)÷1313+1.76]×(0.75÷634),
=[(-414.2)÷1313+1.76]×
0.75 |
674 |
=[-
414.2 |
1313 |
2310.88 |
1313 |
0.75 |
674 |
=
1896.68 |
1313 |
0.75 |
674 |
=
142251 |
88496200 |
点评:算式(2)的数据较大,计算时要细心,注意通分通分约分.
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