题目内容

(1)1125-997 (8)998+1246 (16)4
1
3
+3.2+5
2
3
+6.8
(2)12
2
5
-(1
2
7
+2
2
5
(9)400÷125÷8 (17)25×(37×8)
(3)(
1
4
-
1
6
)×12
(10)1
3
4
×2
4
15
×
4
7

(11)34×(2+
13
34
(18)125×8.8
(4)4.35+4.25+3.65+3.75 (12)3.4×99+3.4 (19)17.15-8.47-1.53
(5)17
5
6
-3
3
4
-4
5
6
(13)
7
9
÷2
1
5
+
5
11
×
2
9
(20)0.125×0.25×32
(6)22.3-2.45-5.3-4.55 (14)(
11
12
+
7
18
+
5
24
)×72
(21)4.25-3
5
6
-(2
1
6
-1
3
4
(7)187.7×11-187.7 (15)43
7
8
×
1
2
+57.125×
1
2
-0.5
(22)2.42÷
3
4
+4.58×1
1
3
-4÷3.
分析:根据加法和乘法的运算定律,减法、除法的运算性质,及加减法的速算方法进行计算.
解答:解:(1)1125-997
=1125-(997+3)+3
=1125-1000+3
=128;
(2)12
2
5
-(1
2
7
+2
2
5

=12
2
5
-2
2
5
-1
2
7

=8
5
7

(3)(
1
3
-
1
4
)×12
=
1
3
×12-
1
6
×12
=4-2
=2;
(4)4.35+4.25+3.65+3.75
=(4.35+3.65)+(4.25+3.75)
=8+8
=16;
(5)17
5
6
-3
3
4
-4
5
6

=17
5
6
-4
5
6
-3
3
4

=9
1
4

(6)22.3-2.45-5.3-4.55
=22.3-5.3-(2.45+4,55)
=17-7
=10;
(7)187.7×11-187.7
=118.7×(11-1)
=118.7×10
=1187;
(8)998+1246
=(998+2)+1246-2
=1000+1246-2
=2244;
(9)400÷125÷8
=400÷(125×8)
=400÷1000
=0.4;
(10)1
3
4
×2
4
15
×
4
7

=
7
4
×
4
7
×2
4
15

=2
4
15

(11)34×(2+
13
34

=34×2+34×
13
34

=68+13
=81;
(12)3.4×99+3.4
=3.4×(99+1)
=3.4×100
=340;
(13)
7
9
÷2
1
5
+
5
11
×
2
9

=(
7
9
+
2
9
)×
5
11

=1×
5
11

=
5
11

(14)(
11
12
+
7
18
+
5
24
)×72
=
11
12
×72+
7
18
×72+
5
24
×72
=66+28+15
=109;
(15)43
7
8
×
1
2
+57.125×
1
2
-0.5
=(43.875+57.125)×0.5-0.5
=101×0.5-0.5
=50.5-0.5
=50;
(16)4
1
3
+3.2+5
2
3
+6.8
=(4
1
3
+5
2
3
)+(3.2+6.8)
=10+10
=20;
(17)25×(37×8)
=25×8×37
=200×37
=7400;
(18)125×8.8
=125×8+125×0.8
=1000+100
=1100;
(19)17.15-8.47-1.53
=17.15-(8.47+1.53)
=17.15-10
=7.15;
(20)0.125×0.25×32
=(0.125×8)×(0.25×4)
=1×1
=1;
(21)4.25-3
5
6
-(2
1
6
-1
3
4

=(4.25+1
3
4
)-(3
5
6
+2
1
6

=6-6
=0;
(22)2.42÷
3
4
+4.58×1
1
3
-4÷3
=(2.42+4.58-1)×
4
3

=6×
4
3

=8;
点评:此题主要考查,利用运算定律、运算性质进行小数、分数四则混合运算的简便计算.
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