题目内容
(2009?静宁县)计算.
(1)55×66÷(11×11)
(2)40.2-4÷80×2.4
(3)3.5×[6.8-(1.6+3.6÷0.9)]÷84
(4)
×[
÷(
×
)]
(5)(
+
)÷(
÷4-
)
(1)55×66÷(11×11)
(2)40.2-4÷80×2.4
(3)3.5×[6.8-(1.6+3.6÷0.9)]÷84
(4)
1 |
8 |
1 |
2 |
3 |
5 |
10 |
9 |
(5)(
1 |
2 |
1 |
4 |
4 |
5 |
1 |
10 |
分析:(1)运用除法的性质简算;
(2)先算除法和乘法,再算减法;
(3)先算小括号内的除法,再算小括号内的加法,然后算中括号内的减法,最后算括号外的乘法和除法;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)两个括号同时计算,第二个括号先算除法,再算减法.
(2)先算除法和乘法,再算减法;
(3)先算小括号内的除法,再算小括号内的加法,然后算中括号内的减法,最后算括号外的乘法和除法;
(4)先算小括号内的,再算中括号内的,最后算括号外的;
(5)两个括号同时计算,第二个括号先算除法,再算减法.
解答:解:(1)55×66÷(11×11),
=55×66÷11÷11,
=55÷11×(66÷11),
=5×6,
=30;
(2)40.2-4÷80×2.4,
=40.2-0.05×2.4,
=40.2-0.12,
=40.08;
(3)3.5×[6.8-(1.6+3.6÷0.9)]÷84,
=3.5×[6.8-(1.6+4)]÷84,
=3.5×[6.8-5.6]÷84,
=3.5×1.2÷84,
=4.2÷84,
=0.05;
(4)
×[
÷(
×
)],
=
×[
÷
],
=
×[
×
],
=
×
,
=
;
(5))(
+
)÷(
÷4-
),
=
÷(
×
-
),
=
÷(
-
),
=
÷
,
=
×10,
=
.
=55×66÷11÷11,
=55÷11×(66÷11),
=5×6,
=30;
(2)40.2-4÷80×2.4,
=40.2-0.05×2.4,
=40.2-0.12,
=40.08;
(3)3.5×[6.8-(1.6+3.6÷0.9)]÷84,
=3.5×[6.8-(1.6+4)]÷84,
=3.5×[6.8-5.6]÷84,
=3.5×1.2÷84,
=4.2÷84,
=0.05;
(4)
1 |
8 |
1 |
2 |
3 |
5 |
10 |
9 |
=
1 |
8 |
1 |
2 |
2 |
3 |
=
1 |
8 |
1 |
2 |
3 |
2 |
=
1 |
8 |
3 |
4 |
=
3 |
32 |
(5))(
1 |
2 |
1 |
4 |
4 |
5 |
1 |
10 |
=
3 |
4 |
4 |
5 |
1 |
4 |
1 |
10 |
=
3 |
4 |
1 |
5 |
1 |
10 |
=
3 |
4 |
1 |
10 |
=
3 |
4 |
=
15 |
2 |
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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