题目内容
(2003?龙湖区)怎样计算简便就怎样算.
(1)1050+750÷30×25
(2)444×25
(3)
+
÷
(4)5.7-0.81-1.29
(5)120×(
+
-
)
(6)15÷[(
-
)×15].
(1)1050+750÷30×25
(2)444×25
(3)
1 |
2 |
16 |
3 |
4 |
3 |
(4)5.7-0.81-1.29
(5)120×(
1 |
2 |
1 |
8 |
1 |
3 |
(6)15÷[(
9 |
10 |
2 |
3 |
分析:(1)(3)(6)按照四则混合运算的运算顺序和计算法则进行计算;
(2)444变化为4×111,然后运用乘法结合律进行简算;
(4)连减两个数等于减去这两个数的和,可以运用加法结合律进行简算;
(5)可运用乘法分配律进行简算.
(2)444变化为4×111,然后运用乘法结合律进行简算;
(4)连减两个数等于减去这两个数的和,可以运用加法结合律进行简算;
(5)可运用乘法分配律进行简算.
解答:解:(1)1050+750÷30×25,
=1050+25×25,
=1050+625,
=1675;
(2)444×25,
=4×111×25,
=4×25×111,
=100×111,
=11100;
(3)
+
÷
,
=
+
×
,
=
+4,
=4
;
(4)5.7-0.81-1.29,
=5.7-(0.81+1.29),
=5.7-2.1,
=3.6;
(5)120×(
+
-
),
=120×
+120×
-120×
,
=60+15-40,
=35;
(6)15÷[(
-
)×15],
=15÷[
×15],
=15÷
,
=
.
=1050+25×25,
=1050+625,
=1675;
(2)444×25,
=4×111×25,
=4×25×111,
=100×111,
=11100;
(3)
1 |
2 |
16 |
3 |
4 |
3 |
=
1 |
2 |
16 |
3 |
3 |
4 |
=
1 |
2 |
=4
1 |
2 |
(4)5.7-0.81-1.29,
=5.7-(0.81+1.29),
=5.7-2.1,
=3.6;
(5)120×(
1 |
2 |
1 |
8 |
1 |
3 |
=120×
1 |
2 |
1 |
8 |
1 |
3 |
=60+15-40,
=35;
(6)15÷[(
9 |
10 |
2 |
3 |
=15÷[
7 |
30 |
=15÷
7 |
2 |
=
30 |
7 |
点评:此题考查学生的计算能力,细心计算,同时要注意运用恰当的运算定律和性质进行简算.
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