题目内容
计算,能简算的要简算
| 112-12× | ( | 25× |
| 17× |
解:(1)112-12×
,
=112-15,
=97;
(2)(
+
)×32,
=
×32+
×32,
=24+20,
=44;
(3)25×
+9×
,
=25×
+7×
,
=(25+7)×
,
=32×
,
=18;
(4)
×
×16,
=
×(
×16),
=
×2,
=
;
(5)
+
×
,
=
+
,
=
;
(6)17×
,
=(16+1)×
,
=16×
+1×
,
=9+
,
=9
.
分析:(1)先算乘法,再算减法;
(2)运用乘法分配律简算;
(3)先根据积不变规律,把9×
变成7×
,再运用乘法分配律简算;
(4)运用乘法结合律简算;
(5)先算乘法,再算加法;
(6)先把17分解成(16+1),再运用乘法分配律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
=112-15,
=97;
(2)(
=
=24+20,
=44;
(3)25×
=25×
=(25+7)×
=32×
=18;
(4)
=
=
=
(5)
=
=
(6)17×
=(16+1)×
=16×
=9+
=9
分析:(1)先算乘法,再算减法;
(2)运用乘法分配律简算;
(3)先根据积不变规律,把9×
(4)运用乘法结合律简算;
(5)先算乘法,再算加法;
(6)先把17分解成(16+1),再运用乘法分配律简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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