14.76-5.76-![]() | 4 ÷8 ×2![]() |
64 ×![]() | 6 ×5-3 ×2 |
13× +4 ×10 | 198÷198 +![]() |
12.5× +3 ×1.25 | + + +![]() |
(3.7×5 -4.7×3.7)÷![]() | [0.3+( +□)×3]÷0.3=860 |
56×![]() | 18.75-(4.5-7.25) |
3.6×31 +3.14×64 | 132 ÷131 |
3× +4× +5× +6×![]() | 112×(24-4 )÷2.4 |
(81.4+ + + )÷( + + ) | 41.2×8.1+11×9 +53.7×1.9 |
+ + + + + +![]() | + + +…+ . |
(1)14.76-5.76-
,=9-
,=8
;(2)4
÷8
×2
,=
×
×
,=
;(3)64
×
,=
×
,=
;(4)6
×5-3
×2,=(6+
)×5-(3+
)×2,=(6×5+
×5)-(3×2+
×2),=30+
-6-
,=(30-6)+(
-
),=24+
,=26
;(5)13×
+4
×10,=5
+46,=51
;(6)198÷198
+
,=198×
+
,=
+
,=1;
(7)12.5×
+3
×1.25,=1.25×10×
+3
×1.25,=1.25×
+3
×1.25,=1.25×(
+3
),=1.25×5,
=6.25;
(8)
+
+
+
,=
+
+
+
,=1-
+
-
+
-
+
-
,=1-
,=
;(9)(3.7×5
-4.7×3.7)÷
,=3.7×(5
-4.7)÷
,=3.7×1÷
,=3.7÷
,=11.1;
(10)[0.3+(
+□)×3]÷0.3=860,[0.3+(
+□)×3]÷0.3=860,[0.3+1.5+□×3]÷0.3=860,
[1.8+□×3]÷0.3=860,
6+10×□=860,
10×□=854,
□=85.4;
(11)56×
,=(55+1)×
,=55×
+1×
,=54+
,=54
,(12)18.75-(4.5-7.25),
=18.75-4.5+7.25,
=(18.75+7.25)-4.5,
=26-4.5,
=21.5;
(13)3.6×31
+3.14×64,=3.6×31.4+3.14×64,
=3.6×31.4+31.4×6.4,
=(3.6+6.4)×31.4,
=10×31.4,
=314;
(14)132
÷131,=(131+1
)×
,=131×
+1
×
,=1+
×
,=1+
,=1
;(15)3×
+4×
+5×
+6×
,=(3×
+5×
)+(4×
+6×
),=
+
,=2+6,
=8;
(16)112×(24-4
)÷2.4,=112×(24-4.8)×
,=112×(24×
-4.8×
),=112×(10-2),
=112×8,
=896;
(17)(81.4+
+
+
)÷(
+
+
),=(81.4+
)÷
,=(81.4+
)×
,=81.4×
+
×
,=132+1,
=133;
(18)41.2×8.1+11×9
+53.7×1.9,=41.2×8.1+11×9.25+(41.2+12.5)×1.9,
=41.2×8.1+11×9.25+41.2×1.9+12.5×1.9,
=(41.2×8.1+41.2×1.9)+11×9.25+12.5×1.9,
=41.2×(8.1+1.9)+11×(8+1.25)+12.5×1.9,
=41.2×10+11×8+11×1.25+1.25×19;
=412+88+1.25×(11+19),
=500+1.25×30,
=500+37.5,
=537.5;
(19)
+
+
+
+
+
+
,=
+
+
+
+
+
+
,=1-
+
-
+
-
+
-
+
-
+
-
+
-
,=1-
,=
;(20)
+
+
+…+
,=
×(1-
+
-
+
-
+…+
-
),=
×(1-
),=
×
,=
.分析:(1)按照从左向右的顺序进行计算;
(2)按照从左向右的顺序进行计算;
(3)把带分数化成假分数,再约分计算;
(4)根据乘法分配律进行计算;
(5)先算乘法,再算减法;
(6)先算乘法,再算加法;
(7)根据乘法分配律进行计算;
(8)根据分数的拆项进行计算;
(9)小括号里面的根据乘法分配律进行计算,再算除法;
(10)把□看作未知数,根据等式的性质进行解方程即可;
(11)根据乘法分配律进行计算;
(12)去掉括号,再根据加法交换律进行计算;
(13)根据乘法分配律进行计算;
(14)根据乘法分配律进行计算;
(15)根据加法交换律和结合律进行计算;
(16)根据乘法分配律进行计算;
(17)先算小括号里面的加法,根据乘法分配律进行计算;
(18)根据乘法分配律进行计算;
(19)根据分数的拆项进行计算;
(20)根据分数的拆项进行计算.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.