题目内容
脱式计算(第1和第2小题用简便方法计算)
(1)14.5×64+64×4.5
(2)2.5×32×12.5
(3)(
+
)÷
+
(4)168.1÷(4.3×2-0.4)
(1)14.5×64+64×4.5
(2)2.5×32×12.5
(3)(
4 |
5 |
1 |
4 |
7 |
3 |
7 |
10 |
(4)168.1÷(4.3×2-0.4)
分析:根据四则混合运算的运算顺序和计算法则进行计算即可,注意运算定律的使用.
解答:解:①14.5×64+64×4.5,
=(14.5+4.5)×64,
=19×64,
=1216;
②2.5×32×12.5,
=2.5×(4×8)×12.5,
=(2.5×4)×(8×12.5),
=10×100,
=1000;
③(
+
)÷
+
,
=
×
+
,
=
+
,
=1
;
④168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
=(14.5+4.5)×64,
=19×64,
=1216;
②2.5×32×12.5,
=2.5×(4×8)×12.5,
=(2.5×4)×(8×12.5),
=10×100,
=1000;
③(
4 |
5 |
1 |
4 |
7 |
3 |
7 |
10 |
=
21 |
20 |
3 |
7 |
7 |
10 |
=
9 |
20 |
14 |
20 |
=1
3 |
20 |
④168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
点评:细心计算,灵活使用运算定律进行简算.
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