题目内容
(1)75×4.67+17.9×2.5
(2)(
×1
×
)÷(
×
×
)
(3)456÷123×789÷456÷789×123
(4)3
+
×1
-2
÷120.
(2)(
| 4 |
| 7 |
| 1 |
| 9 |
| 4 |
| 11 |
| 2 |
| 11 |
| 2 |
| 7 |
| 2 |
| 9 |
(3)456÷123×789÷456÷789×123
(4)3
| 3 |
| 4 |
| 33 |
| 4 |
| 2 |
| 5 |
| 2 |
| 5 |
分析:(1)75=25×5,然后再根据乘法分配律进行简算;
(2)根据除法的性质进行简算;
(3)根据乘法交换律和结合律进行简算;
(4)先算乘法和除法,再算加法,最后算减法.
(2)根据除法的性质进行简算;
(3)根据乘法交换律和结合律进行简算;
(4)先算乘法和除法,再算加法,最后算减法.
解答:解:(1)75×4.67+17.9×2.5,
=(25×3)×4.67+1.79×25,
=25×14.01+1.79×25,
=25×(14.01+1.79),
=25×15.8,
=395;
(2)(
×1
×
)÷(
×
×
),
=
×1
×
÷
÷
÷
,
=(
÷
)×(1
÷
)×(
÷
),
=2×5××2,
=10×2,
=20;
(3)456÷123×789÷789×123,
=(456÷456)×(123÷123)×(789÷789),
=1×1×1,
=1;
(4)3
+
×1
-2
÷120,
=3
+11.55-0.02
=15.3-0.02,
=15.28.
=(25×3)×4.67+1.79×25,
=25×14.01+1.79×25,
=25×(14.01+1.79),
=25×15.8,
=395;
(2)(
| 4 |
| 7 |
| 1 |
| 9 |
| 4 |
| 11 |
| 2 |
| 11 |
| 2 |
| 7 |
| 2 |
| 9 |
=
| 4 |
| 7 |
| 1 |
| 9 |
| 4 |
| 11 |
| 2 |
| 11 |
| 2 |
| 7 |
| 2 |
| 9 |
=(
| 4 |
| 7 |
| 2 |
| 7 |
| 1 |
| 9 |
| 2 |
| 9 |
| 4 |
| 11 |
| 2 |
| 11 |
=2×5××2,
=10×2,
=20;
(3)456÷123×789÷789×123,
=(456÷456)×(123÷123)×(789÷789),
=1×1×1,
=1;
(4)3
| 3 |
| 4 |
| 33 |
| 4 |
| 2 |
| 5 |
| 2 |
| 5 |
=3
| 3 |
| 4 |
=15.3-0.02,
=15.28.
点评:考查了运算定律与简便运算,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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