题目内容
下面各题,能简算的要简算.
(1)30.1-16.8÷3.5×6.2
(2)27×99
(3)
×2.5×
×0.4
(4)
÷8+
×
(5)15×
×(
×
)
(6)
÷[(
-
)÷
].
解:
(1)30.1-16.8÷3.5×6.2,
=30.1-4.8×6.2,
=30.1-29.76,
=0.34;
(2)27×99,
=27×(100-1),
=27×100-27×1,
=2700-27,
=2673;
(3)
×2.5×
×0.4,
=(
×
)×(0.4×2.5),
=1×1,
=1;
(4)
÷8+
×
,
=
×
+
×
,
=
×(
+
),
=
×1,
=
;
(5)15×
×(
×
),
=(15×
)×(
×
),
=10×
,
=1;
(6)
÷[(
-
)÷
],
=
÷[
÷
],
=
÷
,
=
.
分析:(1)先计算除法,再计算乘法,最后计算减法;
(2)把99看作100-1,再根据乘法分配律进行简算;
(3)根据乘法交换律和结合律进行简算;
(4)根据乘法分配律进行简算;
(5)根据交换律和结合律进行简算;
(6)先计算小括号里面的减法,再计算中括号里面的除法,最后计算括号外面的除法.
点评:根据题意,先找清运算顺序,然后再进一步计算即可;能简算的要简算.
(1)30.1-16.8÷3.5×6.2,
=30.1-4.8×6.2,
=30.1-29.76,
=0.34;
(2)27×99,
=27×(100-1),
=27×100-27×1,
=2700-27,
=2673;
(3)


=(


=1×1,
=1;
(4)



=




=



=

=

(5)15×



=(15×



=10×

=1;
(6)




=



=


=

分析:(1)先计算除法,再计算乘法,最后计算减法;
(2)把99看作100-1,再根据乘法分配律进行简算;
(3)根据乘法交换律和结合律进行简算;
(4)根据乘法分配律进行简算;
(5)根据交换律和结合律进行简算;
(6)先计算小括号里面的减法,再计算中括号里面的除法,最后计算括号外面的除法.
点评:根据题意,先找清运算顺序,然后再进一步计算即可;能简算的要简算.

练习册系列答案
相关题目