题目内容
29.46-(9.46+3.8) | 15.75+0.65-2.75+3.35 | 102×35 | 85+85×99 |
65.71-4.99 | 125×48 | 360÷45 | (125-30)×8. |
解:(1)29.46-(9.46+3.8),
=29.46-9.46-3.8,
=20-3.8,
=16.2;
(2)15.75+0.65-2.75+3.35,
=(15.75-2.75)+(0.65+3.35),
=13+4,
=17;
(3)102×35,
=(100+2)×35,
=100×35+2×35,
=3500+70,
=3570;
(4)85+85×99,
=85×(1+99),
=85×100,
=8500;
(5)65.71-4.99,
=65.71-(5-0.01),
=65.71-5+0.01,
=60.71+0.01,
=60.72;
(6)125×48,
=125×8×6,
=1000×6,
=6000;
(7)360÷45,
=(360÷9)÷(45÷9),
=40÷5,
=8;
(8)(125-30)×8,
=125×8-30×8,
=1000-240,
=760.
分析:(1)根据减法的性质简算;
(2)运用加法交换律和结合律简算;
(3)先把102分解成100+2,再运用乘法分配律简算;
(4)(8)运用乘法分配律简算;
(5)运用凑整法简算;
(6)先把48分解成8×6简算;
(7)运用商不变性质简算.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
=29.46-9.46-3.8,
=20-3.8,
=16.2;
(2)15.75+0.65-2.75+3.35,
=(15.75-2.75)+(0.65+3.35),
=13+4,
=17;
(3)102×35,
=(100+2)×35,
=100×35+2×35,
=3500+70,
=3570;
(4)85+85×99,
=85×(1+99),
=85×100,
=8500;
(5)65.71-4.99,
=65.71-(5-0.01),
=65.71-5+0.01,
=60.71+0.01,
=60.72;
(6)125×48,
=125×8×6,
=1000×6,
=6000;
(7)360÷45,
=(360÷9)÷(45÷9),
=40÷5,
=8;
(8)(125-30)×8,
=125×8-30×8,
=1000-240,
=760.
分析:(1)根据减法的性质简算;
(2)运用加法交换律和结合律简算;
(3)先把102分解成100+2,再运用乘法分配律简算;
(4)(8)运用乘法分配律简算;
(5)运用凑整法简算;
(6)先把48分解成8×6简算;
(7)运用商不变性质简算.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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