题目内容
脱式计算:(写出主要过程)
56×125-4228÷7;
7
+
×(2
-1
);
6.15÷2
-
×(
+4.36);
0.8×(0.7-0.175)+9.278÷3.2;
[2.1+7÷(3
-1
).
56×125-4228÷7;
7
3 |
4 |
5 |
8 |
3 |
4 |
3 |
20 |
6.15÷2
1 |
2 |
1 |
3 |
1 |
20 |
0.8×(0.7-0.175)+9.278÷3.2;
[2.1+7÷(3
1 |
12 |
5 |
8 |
考点:整数四则混合运算,运算定律与简便运算,小数四则混合运算,整数、分数、小数、百分数四则混合运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算乘法和除法,再算减法;
(2)先算减法,再算乘法,最后算加法;
(3)先算除法和加法,再算乘法,最后算减法;
(4)先算减法和除法,再算乘法,最后算减法;
(5)先算减法,再算除法,最后算加法.
(2)先算减法,再算乘法,最后算加法;
(3)先算除法和加法,再算乘法,最后算减法;
(4)先算减法和除法,再算乘法,最后算减法;
(5)先算减法,再算除法,最后算加法.
解答:
解:(1)56×125-4228÷7
=7000-604
=6396;
(2)7
+
×(2
-1
)
=7
+
×
=7
+1
=8
;
(3)6.15÷2
-
×(
+4.36)
=2.46-
×4.41
=2.46-1.47
=0.99;
(4)0.8×(0.7-0.175)+9.278÷3.2
=0.8×0.525+2.899375
=0.42+2.899375
=3.319375;
(5)2.1+7÷(3
-1
)
=2.1+7×
=2.1+4.8
=6.9.
=7000-604
=6396;
(2)7
3 |
4 |
5 |
8 |
3 |
4 |
3 |
20 |
=7
3 |
4 |
5 |
8 |
8 |
5 |
=7
3 |
4 |
=8
3 |
4 |
(3)6.15÷2
1 |
2 |
1 |
3 |
1 |
20 |
=2.46-
1 |
3 |
=2.46-1.47
=0.99;
(4)0.8×(0.7-0.175)+9.278÷3.2
=0.8×0.525+2.899375
=0.42+2.899375
=3.319375;
(5)2.1+7÷(3
1 |
12 |
5 |
8 |
=2.1+7×
24 |
35 |
=2.1+4.8
=6.9.
点评:混合运算的关键是抓住运算顺序,正确把握运算顺序,适当把小数分数转化计算即可.
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