题目内容
计算下面各题,能简算的就简算.
| 1- | 3+ | |
| 78×150%-78× |
解:①1-
÷
-
,
=1-
,
=1-(
),
=1-1,
=0;
②3+
×
÷
,
=3+
×
,
=3+
,
=3
;
③
÷(
-
)×
=
÷
×
,
=
×
×
,
=
;
④
×
+
÷
,
=(
)×
,
=1×
,
=
;
⑤78×150%-78×
=78×(150%-
),
=78×1,
=78;
⑥
×[1÷(
+
)]
=
×(1×
),
=
×
,
=
.
分析:第④⑤可用乘法分配律简算,其它题目按照先算乘除再算加减,有括号的先算括号里面的运算顺序计算.
点评:乘法分配律是常用的简算方法,记住它的形式,灵活运用.
=1-
=1-(
=1-1,
=0;
②3+
=3+
=3+
=3
③
=
=
=
④
=(
=1×
=
⑤78×150%-78×
=78×(150%-
=78×1,
=78;
⑥
=
=
=
分析:第④⑤可用乘法分配律简算,其它题目按照先算乘除再算加减,有括号的先算括号里面的运算顺序计算.
点评:乘法分配律是常用的简算方法,记住它的形式,灵活运用.
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