题目内容
脱式计算
(1)(
+2
-
)×12
(2)[47-(18.75-1÷
)×2
]÷0.46
(3)75%×1.375+5.625×75%+0.75
(4)77×13+225×999+510.
(1)(
1 |
3 |
1 |
6 |
5 |
12 |
(2)[47-(18.75-1÷
8 |
15 |
6 |
25 |
(3)75%×1.375+5.625×75%+0.75
(4)77×13+225×999+510.
分析:算式(1)(3)可根据乘法分配律进行计算;
算式(2)可根据乘法分配律计算中括号内的乘法算式;
算式(4)可将13拆分为10+3,999为1000-1后根据乘法分配律计算.
算式(2)可根据乘法分配律计算中括号内的乘法算式;
算式(4)可将13拆分为10+3,999为1000-1后根据乘法分配律计算.
解答:解:(1)(
+2
-
)×12
=
×12+
×12-
×12,
=4+26-5,
=25;
(2)[47-(18.75-1÷
)×2
]÷0.46
=[47-(18.75-
)×
]÷0.46,
=[47-(18.75×
-1.875×
)]÷0.46,
=[47-(42-4.2)]÷0.46,
=[47-37.8]÷0.46,
=9.2÷0.46,
=20;
(3)75%×1.375+5.625×75%+0.75
=0.75×1.375+5.625×0.75+0.75,
=(1.375+5.625+1)×0.75,
=8×0.75,
=6;
(4)77×13+225×999+510.
=77×(10+3)+225×(1000-1)+510,
=77×10+77×3+225×1000-225+510,
=770+231+225000-225+510,
=226286.
1 |
3 |
1 |
6 |
5 |
12 |
=
1 |
3 |
13 |
6 |
5 |
12 |
=4+26-5,
=25;
(2)[47-(18.75-1÷
8 |
15 |
6 |
25 |
=[47-(18.75-
15 |
8 |
56 |
25 |
=[47-(18.75×
56 |
25 |
56 |
25 |
=[47-(42-4.2)]÷0.46,
=[47-37.8]÷0.46,
=9.2÷0.46,
=20;
(3)75%×1.375+5.625×75%+0.75
=0.75×1.375+5.625×0.75+0.75,
=(1.375+5.625+1)×0.75,
=8×0.75,
=6;
(4)77×13+225×999+510.
=77×(10+3)+225×(1000-1)+510,
=77×10+77×3+225×1000-225+510,
=770+231+225000-225+510,
=226286.
点评:本题中的四个算式主要考查了学生灵活运用乘法分配律进行简便计算的能力.
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