题目内容
下面各题怎样简便就怎样算.
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1-
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分析:(1)先算小括号里面的减法,再算中括号里面的乘法,最后计算括号外面的除法;
(2)先算小括号里面的乘法,再从左往右计算算括号外面的乘除法;
(3)先将小数变为分数,再根据乘法交换律和结合律计算即可求解;
(4)先将除法变为乘法,再根据乘法分配律进行计算;
(5)根据乘法分配律进行计算;
(6)先算除法,再算减法.
(2)先算小括号里面的乘法,再从左往右计算算括号外面的乘除法;
(3)先将小数变为分数,再根据乘法交换律和结合律计算即可求解;
(4)先将除法变为乘法,再根据乘法分配律进行计算;
(5)根据乘法分配律进行计算;
(6)先算除法,再算减法.
解答:解:(1)
÷[(
-
)×4]
=
÷[
×4]
=
÷
=
;
(2)
÷(
×3)×5
=
÷
×5
=
×5
=1
;
(3)
×8×
×1.25
=
×8×
×
=(
×
)×(8×
)
=1×13
=13;
(4)
×36+34÷
=
×36+34×
=
×(36+34)
=
×70
=30;
(5)(
+
)×
=
×
+
×
=
+
=
;
(6)1-
÷
=1-
=
.
3 |
5 |
4 |
5 |
1 |
2 |
=
3 |
5 |
3 |
10 |
=
3 |
5 |
6 |
5 |
=
1 |
2 |
(2)
1 |
5 |
4 |
15 |
=
1 |
5 |
4 |
5 |
=
1 |
4 |
=1
1 |
4 |
(3)
4 |
5 |
13 |
8 |
=
4 |
5 |
13 |
8 |
5 |
4 |
=(
4 |
5 |
5 |
4 |
13 |
8 |
=1×13
=13;
(4)
3 |
7 |
7 |
3 |
=
3 |
7 |
3 |
7 |
=
3 |
7 |
=
3 |
7 |
=30;
(5)(
5 |
8 |
5 |
6 |
4 |
25 |
=
5 |
8 |
4 |
25 |
5 |
6 |
4 |
25 |
=
1 |
10 |
2 |
15 |
=
7 |
30 |
(6)1-
3 |
8 |
3 |
5 |
=1-
5 |
8 |
=
3 |
8 |
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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(1) |
(2) |
一个数除以
2,等于这个数乘________.
(3) |
(4) |
一个数除以
4,等于这个数乘________.
(5) |
(6) |
一个数除以
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(7) |
(8) |
一个数除以
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下面各题怎么简便就怎么算:①
32.4×0.5=②
48×0.25=③
12.3÷5=④
7÷8=