题目内容
脱式计算,能简算的要简算. 27.9-13.06+2.1 |
4.7×11-4.7 | 28.8×6.3-6.3×18.8 |
4.8+2.4×98 | 5.37-(2.37-1.8) | 20.01-13.78+6.78. |
考点:小数四则混合运算,运算定律与简便运算
专题:数的运算
分析:(1)运用加法交换律与结合律简算.
(2)(3)运用乘法分配律简算.
(4)把98看作2×49,原式进一步变为4.8+4.8×49,运用乘法分配律简算.
(5)(6)运用减法的性质简算.
(2)(3)运用乘法分配律简算.
(4)把98看作2×49,原式进一步变为4.8+4.8×49,运用乘法分配律简算.
(5)(6)运用减法的性质简算.
解答:
解:(1)27.9-13.06+2.1
=(27.9+2.1)-13.06
=30-13.06
=16.94
(2)4.7×11-4.7
=4.7×(11-1)
=4.7×10
=47
(3)28.8×6.3-6.3×18.8
=(28.8-18.8)×6.3
=10×6.3
=63
(4)4.8+2.4×98
=4.8+2.4×2×49
=4.8+4.8×49
=4.8×(1+49)
=4.8×50
=240
(5)5.37-(2.37-1.8)
=5.37-2.37+1.8
=3+1.8
=4.8
(6)20.01-13.78+6.78
=20.01-(13.78-6.78)
=20.01-7
=13.01
=(27.9+2.1)-13.06
=30-13.06
=16.94
(2)4.7×11-4.7
=4.7×(11-1)
=4.7×10
=47
(3)28.8×6.3-6.3×18.8
=(28.8-18.8)×6.3
=10×6.3
=63
(4)4.8+2.4×98
=4.8+2.4×2×49
=4.8+4.8×49
=4.8×(1+49)
=4.8×50
=240
(5)5.37-(2.37-1.8)
=5.37-2.37+1.8
=3+1.8
=4.8
(6)20.01-13.78+6.78
=20.01-(13.78-6.78)
=20.01-7
=13.01
点评:完成本题要注意分析式中数据,运用合适的运算定律或性质进行简便计算.
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