(2004?南京)脫式計算.(能簡算的要簡算)
①14.8-44.08÷5.8
②7.5×
2
3
+7.5÷
3
4

1
4
+
3
7
+
4
7
÷4
④3.35×6.4×2+6.7×3.6.
分析:①先算除法,再算減法;
②把除法改為乘法,運用乘法分配律簡算;
③先算除法,運用加法結合律計算;
④先運用乘法交換律與結合律計算3.35×6.4×2,再運用乘法分配律簡算.
解答:解:①14.8-44.08÷5.8,
=14.8-7.6,
=7.2;

②7.5×
2
3
+7.5÷
3
4
,
=7.5×
2
3
+7.5×
4
3
,
=7.5×(
2
3
+
4
3
),
=7.5×2,
=15;

1
4
+
3
7
+
4
7
÷4,
=
1
4
+
3
7
+
4
7
×
1
4
,
=
1
4
+
3
7
+
1
7
,
=
1
4
+(
3
7
+
1
7
),
=
1
4
+
4
7
,
=
23
28
;

④3.35×6.4×2+6.7×3.6,
=(3.35×2)×6.4+6.7×3.6,
=6.7×6.4+6.7×3.6,
=6.7×(6.4+3.6),
=6.7×10,
=67.
點評:此題考查了小數(shù)、分數(shù)的四則混合運算,注意運算順序和運算法則,靈活運用所學的運算定律簡便計算.
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