题目内容

下面各题,怎样简便就怎样算.
(1)2.15+8.73+1.27+7.85 (2)11.87-(8.2+1.87) (3)5.42-3.87-1.13
(3)4.38-1.56+0.62-0.44 (4)0.4×270×2. (6)(40+1.25)×8
(7)(12.5-0.05)×8  (8)2.6×8.5+8.5×7.4 (9)9.9×6.9-6.9×3.9
(10)5.6×99+5.6  (11)2.5×(1.9+1.9+1.9+1.9) (12)7.2÷1.25÷8.
分析:充分利用运用加法交换律、结合律;乘法交换律、结合律、分配律;减法的运算规律;除法的运算规律进行简算.
解答:
解:(1)2.15+8.73+1.27+7.85
=(2.15+7.85)+(8.73+1.27),
=10+10,
=20;
(2)11.87-(8.2+1.87),
=11.87-1.87-8.2,
=10-8.2,
=1.8;
(3)5.42-3.87-1.13,
=5.42-5,
=0.42;
(4)4.38-1.56+0.62-0.44,
=(4.38+0.62)-(1.56+0.44),
=5-2,
=3;
(5)0.4×270×2.5,
=(0.4×2.5)×270,
=270;
(6)(40+1.25)×8,
=40×8+1.25×8,
=320+10,
=330;
(7)(12.5-0.05)×8,
=12.5×8-0.05×8,
=100-0.4,
=99.6;
(8)2.6×8.5+8.5×7.4,
=(2.6+7.4)×8.5,
=85;
(9)9.9×6.9-6.9×3.9,
=(9.9-3.9)×6.9,
=6×6.9,
=41.4;
(10)5.6×99+5.6,
=5.6×(99+1),
=560;
(11)2.5×(1.9+1.9+1.9+1.9),
=2.5×4×1.9,
=10×1.9,
=19;
























(12)7.2÷1.25÷8,
=7.2÷8÷1.25,
=0.9÷1.25,
=0.72.
点评:此题考查利用运算定律简算整数、小数的四则混合运算.
练习册系列答案
相关题目

违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com

精英家教网