题目内容
用自己喜欢的方法计算.
390÷15×45-120
1÷[(
-
)×
]
67×9.9+6.7
5.4+(3.87+1.03)÷0.07.
390÷15×45-120
1÷[(
5 |
12 |
1 |
6 |
4 |
7 |
67×9.9+6.7
5.4+(3.87+1.03)÷0.07.
考点:小数四则混合运算,运算定律与简便运算,分数的四则混合运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算除法和乘法,再算减法.
(2)先算小括号内的,再算中括号内的,最后算括号外的.
(3)运用乘法分配律简算.
(4)先算括号内的,再算括号外的除法,最后算括号外的加法.
(2)先算小括号内的,再算中括号内的,最后算括号外的.
(3)运用乘法分配律简算.
(4)先算括号内的,再算括号外的除法,最后算括号外的加法.
解答:
解:(1)390÷15×45-120
=26×45-120
=1170-120
=1050;
(2)1÷[(
-
)×
]
=1÷[
×
]
=1÷
=7;
(3)67×9.9+6.7
=67×(9.9+1)
=67×10.1
=67×(10+0.1)
=67×10+0.1×67
=670+6.7
=676.7;
(4)5.4+(3.87+1.03)÷0.07
=5.4+4.9÷0.07
=5.4+70
=75.4.
=26×45-120
=1170-120
=1050;
(2)1÷[(
5 |
12 |
1 |
6 |
4 |
7 |
=1÷[
1 |
4 |
4 |
7 |
=1÷
1 |
7 |
=7;
(3)67×9.9+6.7
=67×(9.9+1)
=67×10.1
=67×(10+0.1)
=67×10+0.1×67
=670+6.7
=676.7;
(4)5.4+(3.87+1.03)÷0.07
=5.4+4.9÷0.07
=5.4+70
=75.4.
点评:考查了四则混合运算,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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