题目内容
(1)1125-997 | (8)998+1246 | (16)4
| ||||||||||||||
(2)12
|
(9)400÷125÷8 | (17)25×(37×8) | ||||||||||||||
(3)(
|
(10)1
(11)34×(2+
|
(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
|
(13)
|
(20)0.125×0.25×32 | ||||||||||||||
(6)22.3-2.45-5.3-4.55 | (14)(
|
(21)4.25-3
| ||||||||||||||
(7)187.7×11-187.7 | (15)43
|
(22)2.42÷
|
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
-(1
+2
)
=12
-2
-1
=8
;
(3)(
-
)×12
=
×12-
×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
-3
-4
=17
-4
-3
=9
;
(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
×2
×
=
×
×2
=2
;
(11)34×(2+
)
=34×2+34×
=68+13
=81;
(12)3.4×99+3.4
=3.4×(99+1)
=3.4×100
=340;
(13)
÷2
+
×
=(
+
)×
=1×
=
;
(14)(
+
+
)×72
=
×72+
×72+
×72
=66+28+15
=109;
(15)43
×
+57.125×
-0.5
=(43.875+57.125)×0.5-0.5
=101×0.5-0.5
=50.5-0.5
=50;
(16)4
+3.2+5
+6.8
=(4
+5
)+(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
-(2
-1
)
=(4.25+1
)-(3
+2
)
=6-6
=0;
(22)2.42÷
+4.58×1
-4÷3
=(2.42+4.58-1)×
=6×
=8;
=1125-(997+3)+3
=1125-1000+3
=128;
(2)12
2 |
5 |
2 |
7 |
2 |
5 |
=12
2 |
5 |
2 |
5 |
2 |
7 |
=8
5 |
7 |
(3)(
1 |
3 |
1 |
4 |
=
1 |
3 |
1 |
6 |
=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 |
4 |
5 |
6 |
=17
5 |
6 |
5 |
6 |
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 |
4 |
15 |
4 |
7 |
=
7 |
4 |
4 |
7 |
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 |
1 |
5 |
5 |
11 |
2 |
9 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
(14)(
11 |
12 |
7 |
18 |
5 |
24 |
=
11 |
12 |
7 |
18 |
5 |
24 |
=66+28+15
=109;
(15)43
7 |
8 |
1 |
2 |
1 |
2 |
=(43.875+57.125)×0.5-0.5
=101×0.5-0.5
=50.5-0.5
=50;
(16)4
1 |
3 |
2 |
3 |
=(4
1 |
3 |
2 |
3 |
=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 |
1 |
6 |
3 |
4 |
=(4.25+1
3 |
4 |
5 |
6 |
1 |
6 |
=6-6
=0;
(22)2.42÷
3 |
4 |
1 |
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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