题目内容
脱式计算(能简算的就简算).
2.84×
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|
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24.5÷1.25÷8 | 3.6÷2.8+7.4-7.2. |
考点:整数、分数、小数、百分数四则混合运算,运算定律与简便运算
专题:运算顺序及法则
分析:(1)根据乘法分配律进简算;
(2)先算减法,再算除法,最后算乘法;
(3)根据加法交换律和结合律进行简算;
(4)根据乘法分配律进行简算;
(5)根据除法的性质进行简算;
(6)先算除法,再根据加法结合律进行简算.
(2)先算减法,再算除法,最后算乘法;
(3)根据加法交换律和结合律进行简算;
(4)根据乘法分配律进行简算;
(5)根据除法的性质进行简算;
(6)先算除法,再根据加法结合律进行简算.
解答:
解:(1)2.84×
+4.16÷
=2.84×
+4.16×
=(2.84+4.16)×
=7×
=3;
(2)
×[1÷(
-
)]
=
×[1÷
]
=
×
=
;
(3)
+4
+
+5.2
=(
+
)+(4
+5.2)
=1+10
=11;
(4)
×(
×17-
)
=
×[
×(17-1)]
=
×[
×16]
=
×16×
=13×
=9;
(5)24.5÷1.25÷8
=24.5÷(1.25×8)
=24.5÷10
=2.45;
(6)3.6÷2.8+7.4-7.2
=
+(7.4-7.2)
=
+0.2
=1
.
3 |
7 |
7 |
3 |
=2.84×
3 |
7 |
3 |
7 |
=(2.84+4.16)×
3 |
7 |
=7×
3 |
7 |
=3;
(2)
3 |
8 |
7 |
10 |
3 |
20 |
=
3 |
8 |
11 |
20 |
=
3 |
8 |
20 |
11 |
=
15 |
22 |
(3)
5 |
7 |
4 |
5 |
2 |
7 |
=(
5 |
7 |
2 |
7 |
4 |
5 |
=1+10
=11;
(4)
13 |
16 |
9 |
13 |
9 |
13 |
=
13 |
16 |
9 |
13 |
=
13 |
16 |
9 |
13 |
=
13 |
16 |
9 |
13 |
=13×
9 |
13 |
=9;
(5)24.5÷1.25÷8
=24.5÷(1.25×8)
=24.5÷10
=2.45;
(6)3.6÷2.8+7.4-7.2
=
9 |
7 |
=
9 |
7 |
=1
17 |
35 |
点评:此题主要考查分数、整数、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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