题目内容
| 计算(能简算的要简算) (
|
18+
| ||||||||||
19×(
|
| ||||||||||
|
55×(
| ||||||||||
76×
|
分析:(1)(3)(5)(6)(7)运用乘法分配律简算;
(2)(4)先算乘法,再算加法.
(2)(4)先算乘法,再算加法.
解答:解:(1)(
+
)×24,
=
×24+
×24,
=15+6,
=21;
(2)18+
×
,
=18+
,
=18
;
(3)19×(
+
),
=19×
+19×
,
=3
+6,
=9
;
(4)
×
+
,
=
+
,
=
;
(5)
×(
+
),
=
×
,
=
;
(6)55×(
+
),
=55×
+
×55,
=11
+7,
=18
;
(7)76×
+74×
,
=(76+74)×
,
=150×
,
=16.
| 5 |
| 8 |
| 1 |
| 4 |
=
| 5 |
| 8 |
| 1 |
| 4 |
=15+6,
=21;
(2)18+
| 3 |
| 11 |
| 3 |
| 12 |
=18+
| 3 |
| 44 |
=18
| 3 |
| 44 |
(3)19×(
| 7 |
| 38 |
| 6 |
| 19 |
=19×
| 7 |
| 38 |
| 6 |
| 19 |
=3
| 1 |
| 2 |
=9
| 1 |
| 2 |
(4)
| 3 |
| 8 |
| 4 |
| 5 |
| 2 |
| 5 |
=
| 3 |
| 10 |
| 2 |
| 5 |
=
| 7 |
| 10 |
(5)
| 4 |
| 7 |
| 3 |
| 8 |
| 5 |
| 12 |
=
| 4 |
| 7 |
| 19 |
| 24 |
=
| 19 |
| 42 |
(6)55×(
| 7 |
| 33 |
| 7 |
| 55 |
=55×
| 7 |
| 33 |
| 7 |
| 55 |
=11
| 2 |
| 3 |
=18
| 2 |
| 3 |
(7)76×
| 8 |
| 75 |
| 8 |
| 75 |
=(76+74)×
| 8 |
| 75 |
=150×
| 8 |
| 75 |
=16.
点评:此题考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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