题目内容
脱式计算 8.4×0.26+
|
|
31.7-0.5×0.7-1.65 | ||||||||
0.8×(3.2-
|
42.3×18+7.7×18 |
|
分析:完成本题据四则混合运算法则计算即可:先算乘除,再算加减,有括号的要先算括号里面的.同时要注意分析式中数据,能简算的要简算.
解答:解:(1)8.4×0.26+
=2.184+0.625,
=2.809.
(2)
+
-
=
-
,
=
;
(3)31.7-0.5×0.7-1.65
=31.7-0.35-1.65,
=31.7-(0.35+1.65),
=31.7-2,
=29.7.
(4)0.8×(3.2-
)
=0.8×(3.2-0.2),
=0.8×3,
=2.4;
(5)42.3×18+7.7×18
=(42.3+7.7)×18,
=50×18,
=900.
(6)
×
+
+2.64×12.5
=
×
+
+33,
=
+
+33,
=34.
5 |
8 |
=2.184+0.625,
=2.809.
(2)
3 |
4 |
7 |
6 |
1 |
7 |
=
23 |
12 |
1 |
7 |
=
149 |
84 |
(3)31.7-0.5×0.7-1.65
=31.7-0.35-1.65,
=31.7-(0.35+1.65),
=31.7-2,
=29.7.
(4)0.8×(3.2-
1 |
5 |
=0.8×(3.2-0.2),
=0.8×3,
=2.4;
(5)42.3×18+7.7×18
=(42.3+7.7)×18,
=50×18,
=900.
(6)
1 |
4 |
3 |
5 |
17 |
20 |
=
1 |
4 |
3 |
5 |
17 |
20 |
=
3 |
20 |
17 |
20 |
=34.
点评:在完成同时含有分数与小数的四则混合运算时,要根据式中数据的特点灵活将式中的小数与分数进行互化.
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