题目内容
计算：
[0.15+（4.74-1.8）÷0.4]×0.8
[（
+1
）×
-
]÷
×[
-（
-
）]
48
÷（243×3.75+24
×41.1+2
×214）
[0.15+（4.74-1.8）÷0.4]×0.8
[（
| 8 |
| 9 |
| 1 |
| 3 |
| 3 |
| 4 |
| 3 |
| 4 |
| 1 |
| 12 |
| 8 |
| 9 |
| 7 |
| 8 |
| 7 |
| 8 |
| 1 |
| 8 |
48
| 3 |
| 5 |
| 3 |
| 10 |
| 43 |
| 100 |
考点：小数四则混合运算,分数的四则混合运算,整数、分数、小数、百分数四则混合运算
专题：运算顺序及法则
分析：①[0.15+（4.74-1.8）÷0.4]×0.8，先算小括号里面的减法，再算中括号里面的除法，然后算中括号里面的加法，最后数乘法；
②[（
+1
）×
-
]÷
，先算小括号里面的加法，再算中括号里面的乘法，然后算中括号里面的减法，最后数除法；
③
×[
-（
-
）]，先算小括号里面的减法，再算中括号里面的减法，最后数乘法；
④48
÷（243×3.75+24
×41.1+2
×214），首先把分数化成小数，再根据因数与积的变化规律、以及乘法分配律简算．
②[（
| 8 |
| 9 |
| 1 |
| 3 |
| 3 |
| 4 |
| 3 |
| 4 |
| 1 |
| 12 |
③
| 8 |
| 9 |
| 7 |
| 8 |
| 7 |
| 8 |
| 1 |
| 8 |
④48
| 3 |
| 5 |
| 3 |
| 10 |
| 43 |
| 100 |
解答：
解：①[0.15+（4.74-1.8）÷0.4]×0.8
=[0.15+2.94÷0.4]×0.8
=[0.15+7.35]×0.8
=7.5×0.8
=6；
②[（
+1
）×
-
]÷
=[
×
-
]÷
=[
-
]÷
=
×12
=11；
③
×[
-（
-
）]
=
×[
-
]
=
×
=
；
④48
÷（243×3.75+24
×41.1+2
×214）
=48.6÷（243×3.75+24.3×41.1+2.43×214）
=48.6÷（2.43×375+2.43×411+2.43×214）
=48.6÷[2.43×（375+411+214）]
=48.6÷[2.43×1000]
=48.6÷2430
=0.02．
=[0.15+2.94÷0.4]×0.8
=[0.15+7.35]×0.8
=7.5×0.8
=6；
②[（
| 8 |
| 9 |
| 1 |
| 3 |
| 3 |
| 4 |
| 3 |
| 4 |
| 1 |
| 12 |
=[
| 20 |
| 9 |
| 3 |
| 4 |
| 3 |
| 4 |
| 1 |
| 12 |
=[
| 5 |
| 3 |
| 3 |
| 4 |
| 1 |
| 12 |
=
| 11 |
| 12 |
=11；
③
| 8 |
| 9 |
| 7 |
| 8 |
| 7 |
| 8 |
| 1 |
| 8 |
=
| 8 |
| 9 |
| 7 |
| 8 |
| 6 |
| 8 |
=
| 8 |
| 9 |
| 1 |
| 8 |
=
| 1 |
| 9 |
④48
| 3 |
| 5 |
| 3 |
| 10 |
| 43 |
| 100 |
=48.6÷（243×3.75+24.3×41.1+2.43×214）
=48.6÷（2.43×375+2.43×411+2.43×214）
=48.6÷[2.43×（375+411+214）]
=48.6÷[2.43×1000]
=48.6÷2430
=0.02．
点评：此题考查的目的是理解掌握小数四则混合运算的顺序以及它们的计算法则，并且能够灵活运用简便方法进行计算．
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