题目内容
计算下列各题、能简算的要简算.
|
|
25-25×
| ||||||||||||||||
(
|
|
|
分析:(1)根据连续减去两个数等于减去这两个数的和简算;
(2)按照从左到右的顺序计算;
(3)(4)运用乘法分配律简算;
(5)把除法变成乘法,再运用乘法交换律简算;
(6)先算小括号里面的减法,再算括号外的乘法,最后算括号外的除法.
(2)按照从左到右的顺序计算;
(3)(4)运用乘法分配律简算;
(5)把除法变成乘法,再运用乘法交换律简算;
(6)先算小括号里面的减法,再算括号外的乘法,最后算括号外的除法.
解答:解:(1)
-
-
,
=
-(
+
),
=2
-2,
=
;
(2)
×
÷
,
=
×
,
=
;
(3)25-25×
,
=25×(1-
),
=25×
,
=
;
(4)(
-
)×20
=
×20-
×20,
=5-1,
=4;
(5)
÷16÷
,
=
×
×
,
=
×
,
=
;
(6)
×(
-
)÷
,
=
×
÷
,
=
×
,
=
.
| 14 |
| 5 |
| 1 |
| 3 |
| 5 |
| 3 |
=
| 14 |
| 5 |
| 1 |
| 3 |
| 5 |
| 3 |
=2
| 4 |
| 5 |
=
| 4 |
| 5 |
(2)
| 2 |
| 3 |
| 5 |
| 4 |
| 10 |
| 9 |
=
| 10 |
| 12 |
| 9 |
| 10 |
=
| 3 |
| 4 |
(3)25-25×
| 99 |
| 100 |
=25×(1-
| 99 |
| 100 |
=25×
| 1 |
| 100 |
=
| 1 |
| 4 |
(4)(
| 1 |
| 4 |
| 1 |
| 20 |
=
| 1 |
| 4 |
| 1 |
| 20 |
=5-1,
=4;
(5)
| 7 |
| 10 |
| 14 |
| 5 |
=
| 7 |
| 10 |
| 5 |
| 14 |
| 1 |
| 16 |
=
| 1 |
| 4 |
| 1 |
| 16 |
=
| 1 |
| 64 |
(6)
| 3 |
| 4 |
| 7 |
| 15 |
| 1 |
| 5 |
| 2 |
| 3 |
=
| 3 |
| 4 |
| 4 |
| 15 |
| 2 |
| 3 |
=
| 1 |
| 5 |
| 3 |
| 2 |
=
| 3 |
| 10 |
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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