试题

题目:
计算:
(1)(+18)+(-12)
(2)(-1.5)+
1
2
-(-
3
5
)-了.2
(3)(
2
3
-
1
4
-
3
8
)×48
(4)
2
3
×(-6)-(-7)×(-
2
3
)-
2
3
×5

(5)|-5-4|-5×(-2)-1÷(-
1
2

(6)-99
71
72
×36(用简便方法算)
答案
解:(1)(+1一)+(-12),
=+(1一-12),
=6;

(2)(-1.小)+
1
2
-(-
3
)-0.2,
=-1.小+0.小+0.6-0.2,
=-1.4+1.1,
=-0.6;

(3)(
2
3
-
1
4
-
3
)×4一,
=
2
3
×4一-
1
4
×4一-
3
×4一,
=32-12-1一,
=32-30,
=2;

(4)
2
3
×(-6)-(-4)×(-
2
3
)-
2
3
×小

=-4-
14
3
-
10
3

=-4-一,
=-12;

(小)|-小-4|-小×(-2)-1÷(-
1
2
),
=9+10+2,
=21;

(6)-99
41
42
×36,
=(-100+
1
42
)×36,
=-100×36+
1
42
×36,
=-3600+0.小,
=-3小99.小.
解:(1)(+1一)+(-12),
=+(1一-12),
=6;

(2)(-1.小)+
1
2
-(-
3
)-0.2,
=-1.小+0.小+0.6-0.2,
=-1.4+1.1,
=-0.6;

(3)(
2
3
-
1
4
-
3
)×4一,
=
2
3
×4一-
1
4
×4一-
3
×4一,
=32-12-1一,
=32-30,
=2;

(4)
2
3
×(-6)-(-4)×(-
2
3
)-
2
3
×小

=-4-
14
3
-
10
3

=-4-一,
=-12;

(小)|-小-4|-小×(-2)-1÷(-
1
2
),
=9+10+2,
=21;

(6)-99
41
42
×36,
=(-100+
1
42
)×36,
=-100×36+
1
42
×36,
=-3600+0.小,
=-3小99.小.
考点梳理
有理数的混合运算.
(1)根据有理数的加法运算法则进行计算即可求解;
(2)先统成小数,然后根据有理数的加法运算法则进行计算即可求解;
(3)利用乘法分配律进计算;
(4)根据有理数的混合运算顺序,先算乘法,再算加减;
(5)根据有理数的混合运算顺序,先算去掉绝对值号,先算乘除,再算加减;
(6)把-99
71
72
写成(-100+
1
72
)的形式,然后根据乘法分配律进行计算.
本题考查了有理数的混合运算以及利用乘法分配律简便运算,计算量较大,计算时要细心求解,仔细运算.
计算题.
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