题目内容
(2007?长汀县)用递等式计算(能简算的要用简便方法计算).
①13×8×125
②8.9×99+1.1×99
③12.12÷(4.3×2-7.4)
④
×
+
÷
⑤
÷(1-
-
)
①13×8×125
②8.9×99+1.1×99
③12.12÷(4.3×2-7.4)
④
4 |
7 |
7 |
24 |
1 |
5 |
6 |
5 |
⑤
1 |
4 |
1 |
2 |
1 |
4 |
分析:第1题根据乘法结合律运算,第2题根据乘法分配律运算,其它题根据四则运算的法则进行计算即可.
解答:解:①13×8×125,
=13×(8×125),
=13×1000,
=13000,
②8.9×99+1.1×99,
(8.9+1.1)×99,
=10×99,
=990,
③12.12÷(4.3×2-7.4),
=12.12÷1.2,
=10.1,
④
×
+
÷
,
=
+
,
=
,
⑤
÷(1-
-
),
=
÷
,
=1.
=13×(8×125),
=13×1000,
=13000,
②8.9×99+1.1×99,
(8.9+1.1)×99,
=10×99,
=990,
③12.12÷(4.3×2-7.4),
=12.12÷1.2,
=10.1,
④
4 |
7 |
7 |
24 |
1 |
5 |
6 |
5 |
=
1 |
6 |
1 |
6 |
=
1 |
3 |
⑤
1 |
4 |
1 |
2 |
1 |
4 |
=
1 |
4 |
1 |
4 |
=1.
点评:解答此题关键是掌握四则混合运算法则,会根据运算定律进行简便运算.
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