题目内容
能简算的要简算.
|
(
|
| ||||||||||||||||||
|
|
(
| ||||||||||||||||||
|
|
72×
|
分析:①②③⑤⑥⑦⑨都可以使用运算定律进行简算,④⑧按计算顺序和计算法则进行计算即可.
解答:解:①
×
×13×11,
=(
×11)×(
×13),
=10×1,
=10;
②(
+
)×
,
=
×
+
×
,
=
+1,
=3
;
③
×21+28×
,
=(21+28)×
,
=49×
,
=13;
④
-
×
,
=
-
,
=
;
⑤
×
+
×
,
=(
+
)×
,
=1×
,
=
;
⑥(
+
)×32,
=
×32+
×32,
=24+20,
=44;
⑦
×
×16,
=
×(
×16),
=
×2,
=
;
⑧
+
×
,
=
+
,
=
;
⑨72×
,
=(71+1)×
,
=71×
+
,
=5+
,
=5
.
| 10 |
| 11 |
| 1 |
| 13 |
=(
| 10 |
| 11 |
| 1 |
| 13 |
=10×1,
=10;
②(
| 4 |
| 5 |
| 3 |
| 10 |
| 10 |
| 3 |
=
| 4 |
| 5 |
| 10 |
| 3 |
| 3 |
| 10 |
| 10 |
| 3 |
=
| 8 |
| 3 |
=3
| 2 |
| 3 |
③
| 13 |
| 49 |
| 13 |
| 49 |
=(21+28)×
| 13 |
| 49 |
=49×
| 13 |
| 49 |
=13;
④
| 4 |
| 5 |
| 4 |
| 5 |
| 5 |
| 6 |
=
| 4 |
| 5 |
| 2 |
| 3 |
=
| 2 |
| 15 |
⑤
| 5 |
| 9 |
| 3 |
| 4 |
| 5 |
| 9 |
| 1 |
| 4 |
=(
| 3 |
| 4 |
| 1 |
| 4 |
| 5 |
| 9 |
=1×
| 5 |
| 9 |
=
| 5 |
| 9 |
⑥(
| 3 |
| 4 |
| 5 |
| 8 |
=
| 3 |
| 4 |
| 5 |
| 8 |
=24+20,
=44;
⑦
| 5 |
| 4 |
| 1 |
| 8 |
=
| 5 |
| 4 |
| 1 |
| 8 |
=
| 5 |
| 4 |
=
| 5 |
| 2 |
⑧
| 1 |
| 5 |
| 2 |
| 9 |
| 3 |
| 10 |
=
| 1 |
| 5 |
| 1 |
| 15 |
=
| 4 |
| 15 |
⑨72×
| 5 |
| 71 |
=(71+1)×
| 5 |
| 71 |
=71×
| 5 |
| 71 |
| 5 |
| 71 |
=5+
| 5 |
| 71 |
=5
| 5 |
| 71 |
点评:计算要细心,同时注意使用运算定律进行简算.
练习册系列答案
相关题目