试题

题目:
计算.
(1)(-6)×(+8);
(2)(-0.36)×(-
2
9
);
(3)(-2
2
3
)×(-2
1
4
);
(4)(-288
2
5
)×0;
(5)2
1
4
×(-1
3
4
)×(-
2
3
)×(-
8
7
);
(6)(-5)×(-8)×0×(-10)×(-15);
(7)(-3
1
3
)×(-0.12)×(-2
1
4
)×33
1
3

(8)(+
1
2
)×|-
2
3
|×2
1
4
×(-5
1
3
);
(9)(-3)×(-4)×(-5)+(-5)×(-7);
(10)(-0.1)×(-1)×(-100)-0.01×(1000).
答案
解:(1)(-6)×(+8),
=-(6×8),
=-48;

(2)(-0.36)×(-
2
9
),
=0.36×
2
9

=0.04×2.
=0.08;

(3)(-2
2
3
)×(-2
1
4
),
=
8
3
×
9
4

=6;

(4)(-288
2
5
)×0=0;
(5)2
1
4
×(-1
3
4
)×(-
2
3
)×(-
8
7
),
=-
9
4
×
7
4
×
2
3
×
8
7

=-3;

(6)(-5)×(-8)×0×(-10)×(-15)=0;

(7)(-3
1
3
)×(-0.12)×(-2
1
4
)×33
1
3

=-
10
3
×0.12×
9
4
×
100
3

=-30;

(8)(+
1
2
)×|-
2
3
|×2
1
4
×(-5
1
3
),
=
1
2
×
2
3
×
9
4
×(-
16
3
),
=-4;

(9)(-3)×(-4)×(-5)+(-5)×(-7),
=-3×4×5+5×7,
=-60+35,
=-25;

(10)(-0.1)×(-1)×(-100)-0.01×(1000),
=-0.1×1×100-0.01×1000,
=-10-10,
=-20.
解:(1)(-6)×(+8),
=-(6×8),
=-48;

(2)(-0.36)×(-
2
9
),
=0.36×
2
9

=0.04×2.
=0.08;

(3)(-2
2
3
)×(-2
1
4
),
=
8
3
×
9
4

=6;

(4)(-288
2
5
)×0=0;
(5)2
1
4
×(-1
3
4
)×(-
2
3
)×(-
8
7
),
=-
9
4
×
7
4
×
2
3
×
8
7

=-3;

(6)(-5)×(-8)×0×(-10)×(-15)=0;

(7)(-3
1
3
)×(-0.12)×(-2
1
4
)×33
1
3

=-
10
3
×0.12×
9
4
×
100
3

=-30;

(8)(+
1
2
)×|-
2
3
|×2
1
4
×(-5
1
3
),
=
1
2
×
2
3
×
9
4
×(-
16
3
),
=-4;

(9)(-3)×(-4)×(-5)+(-5)×(-7),
=-3×4×5+5×7,
=-60+35,
=-25;

(10)(-0.1)×(-1)×(-100)-0.01×(1000),
=-0.1×1×100-0.01×1000,
=-10-10,
=-20.
考点梳理
有理数的乘法.
根据有理数的乘法法则进行运算,先判断出积的符号,再计算绝对值.
此题考查了有理数的运算法则:①运用乘法法则,先确定符号,再把绝对值相乘.
②多个因数相乘,看0因数和积的符号当先,这样做使运算既准确又简单.
计算题.
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