题目内容
脱式计算,能简算的要简算.
①
|
②
|
③
| ||||||||||||||||||
④
|
⑤
|
⑥15×4.6-46×0.5. |
分析:①先算加法,再算减法;
②先算减法,再算加法;
③根据加法交换律和结合律进行计算;
④根据加法交换律进行计算;
⑤根据减法的性质进行计算;
⑥根据乘法分配律进行计算.
②先算减法,再算加法;
③根据加法交换律和结合律进行计算;
④根据加法交换律进行计算;
⑤根据减法的性质进行计算;
⑥根据乘法分配律进行计算.
解答:解:
①
+
-
,
=
-
,
=
;
②
-
+
,
=
+
,
=
;
③
+
+
+0.125,
=(
+
)+(
+0.125),
=1+
,
=1
;
④
-
+
,
=
+
-
,
=1-
,
=
;
⑤
-(
+
),
=
-
-
,
=
-
-
,
=1-
,
=
;
⑥15×4.6-46×0.5,
=15×4.6-4.6×5,
=(15-5)×4.6,
=10×4.6,
=46.
①
1 |
2 |
2 |
5 |
3 |
4 |
=
9 |
10 |
3 |
4 |
=
3 |
20 |
②
3 |
2 |
5 |
6 |
7 |
12 |
=
2 |
3 |
7 |
12 |
=
5 |
4 |
③
2 |
9 |
3 |
8 |
7 |
9 |
=(
2 |
9 |
7 |
9 |
3 |
8 |
=1+
1 |
2 |
=1
1 |
2 |
④
2 |
3 |
2 |
15 |
1 |
3 |
=
2 |
3 |
1 |
3 |
2 |
15 |
=1-
2 |
15 |
=
13 |
15 |
⑤
14 |
9 |
4 |
5 |
5 |
9 |
=
14 |
9 |
4 |
5 |
5 |
9 |
=
14 |
9 |
5 |
9 |
4 |
5 |
=1-
4 |
5 |
=
1 |
5 |
⑥15×4.6-46×0.5,
=15×4.6-4.6×5,
=(15-5)×4.6,
=10×4.6,
=46.
点评:此题主要考查分数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.
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