题目内容
能简便的用简便方法计算.
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(
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1-
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(
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分析:(1)(2)运用乘法分配律简算;
(3)(6)先把除法变成乘法,再运用乘法分配律简算;
(4)先算除法,再算减法;
(5)先算除法,再运用减法的性质简算.
(3)(6)先把除法变成乘法,再运用乘法分配律简算;
(4)先算除法,再算减法;
(5)先算除法,再运用减法的性质简算.
解答:解:(1)
×7+
×11,
=
×(7+11),
=
×18,
=10;
(2)(
-
)×36,
=
×36-
×36,
=21-10,
=11;
(3)
×
+
÷5,
=
×
+
×
,
=
×(
+
),
=
×1,
=
;
(4)1-
÷
,
=1-
,
=
;
(5)
-
÷
-
,
=
-
-
,
=
-(
+
),
=
-1,
=
;
(6)(
+
)÷
,
=(
+
)×
,
=
×
+
×
,
=
+1,
=2
.
| 5 |
| 9 |
| 5 |
| 9 |
=
| 5 |
| 9 |
=
| 5 |
| 9 |
=10;
(2)(
| 7 |
| 12 |
| 5 |
| 18 |
=
| 7 |
| 12 |
| 5 |
| 18 |
=21-10,
=11;
(3)
| 1 |
| 5 |
| 4 |
| 7 |
| 3 |
| 7 |
=
| 1 |
| 5 |
| 4 |
| 7 |
| 3 |
| 7 |
| 1 |
| 5 |
=
| 1 |
| 5 |
| 4 |
| 7 |
| 3 |
| 7 |
=
| 1 |
| 5 |
=
| 1 |
| 5 |
(4)1-
| 7 |
| 9 |
| 7 |
| 8 |
=1-
| 8 |
| 9 |
=
| 1 |
| 9 |
(5)
| 5 |
| 4 |
| 1 |
| 3 |
| 5 |
| 9 |
| 2 |
| 5 |
=
| 5 |
| 4 |
| 3 |
| 5 |
| 2 |
| 5 |
=
| 5 |
| 4 |
| 3 |
| 5 |
| 2 |
| 5 |
=
| 5 |
| 4 |
=
| 1 |
| 4 |
(6)(
| 7 |
| 8 |
| 13 |
| 16 |
| 13 |
| 16 |
=(
| 7 |
| 8 |
| 13 |
| 16 |
| 16 |
| 13 |
=
| 7 |
| 8 |
| 16 |
| 13 |
| 13 |
| 16 |
| 16 |
| 13 |
=
| 14 |
| 13 |
=2
| 1 |
| 13 |
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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