题目内容
(2004?南京)脱式计算.(能简算的要简算)
①14.8-44.08÷5.8
②7.5×
+7.5÷
③
+
+
÷4
④3.35×6.4×2+6.7×3.6.
①14.8-44.08÷5.8
②7.5×
2 |
3 |
3 |
4 |
③
1 |
4 |
3 |
7 |
4 |
7 |
④3.35×6.4×2+6.7×3.6.
分析:①先算除法,再算减法;
②把除法改为乘法,运用乘法分配律简算;
③先算除法,运用加法结合律计算;
④先运用乘法交换律与结合律计算3.35×6.4×2,再运用乘法分配律简算.
②把除法改为乘法,运用乘法分配律简算;
③先算除法,运用加法结合律计算;
④先运用乘法交换律与结合律计算3.35×6.4×2,再运用乘法分配律简算.
解答:解:①14.8-44.08÷5.8,
=14.8-7.6,
=7.2;
②7.5×
+7.5÷
,
=7.5×
+7.5×
,
=7.5×(
+
),
=7.5×2,
=15;
③
+
+
÷4,
=
+
+
×
,
=
+
+
,
=
+(
+
),
=
+
,
=
;
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.
=14.8-7.6,
=7.2;
②7.5×
2 |
3 |
3 |
4 |
=7.5×
2 |
3 |
4 |
3 |
=7.5×(
2 |
3 |
4 |
3 |
=7.5×2,
=15;
③
1 |
4 |
3 |
7 |
4 |
7 |
=
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.
点评:此题考查了小数、分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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