题目内容
能简算的要简算
|
(
|
|
| ||||||||||||||||||||||||
|
|
|
|
分析:(1)(3)(4)(5)直接约分计算即可;
(2)(7)利用乘法分配律简算;
(6)先算乘法,再算减法;
(8)先算减法,再算乘法.
(2)(7)利用乘法分配律简算;
(6)先算乘法,再算减法;
(8)先算减法,再算乘法.
解答:解:(1)
×51=33;
(2)(
-
)×21
=
×21-
×21
=12-7
=5;
(3)
×5×27
=
×27×5
=15×5
=75;
(4)
×
=
;
(5)
×
×14
=
×(
×14)
=
×2
=
;
(6)
-
×
=
-
=
;
(7)
×
+
×
=(
+
)×
=1×
=
;
(8)
×(
-
)
=
×
=
.
| 11 |
| 17 |
(2)(
| 4 |
| 7 |
| 1 |
| 3 |
=
| 4 |
| 7 |
| 1 |
| 3 |
=12-7
=5;
(3)
| 5 |
| 9 |
=
| 5 |
| 9 |
=15×5
=75;
(4)
| 15 |
| 32 |
| 14 |
| 25 |
| 21 |
| 80 |
(5)
| 5 |
| 11 |
| 1 |
| 7 |
=
| 5 |
| 11 |
| 1 |
| 7 |
=
| 5 |
| 11 |
=
| 10 |
| 11 |
(6)
| 3 |
| 5 |
| 3 |
| 5 |
| 1 |
| 2 |
=
| 3 |
| 5 |
| 3 |
| 10 |
=
| 3 |
| 10 |
(7)
| 19 |
| 25 |
| 1 |
| 5 |
| 19 |
| 25 |
| 4 |
| 5 |
=(
| 1 |
| 5 |
| 4 |
| 5 |
| 19 |
| 25 |
=1×
| 19 |
| 25 |
=
| 19 |
| 25 |
(8)
| 7 |
| 8 |
| 3 |
| 4 |
| 2 |
| 3 |
=
| 7 |
| 8 |
| 1 |
| 12 |
=
| 7 |
| 96 |
点评:此题考查分数四则混合运算,抓住运算顺序,掌握数字特点,适当选择运算定律简算.
练习册系列答案
相关题目