简便计算下面各题.(要写出简算过程)
287×99
372-(272+77)
125×(80+8)640÷(80×4)767-252-148213×15+86×15+15268+199125×4×8×25372-197+128.
网友回答
解:(1)287×99,
=287×(100-1),
=287×100-287×1,
=28700-287,
=28413;
(2)372-(272+77),
=372-272-77,
=100-77,
=23;
(3)125×(80+8),
=125×80+125×8,
=10000+1000,
=11000;
(4)640÷(80×4),
=640÷320,
=2;
(5)767-252-148,
=767-(252+148),
=767-400,
=367;
(6)213×15+86×15+15,
=(213+86+1)×15,
=300×15,
=4500;
(7)268+199,
=268+100-1,
=368-1,
=367;
(8)125×4×8×25,
=(125×8)×(4×25),
=1000×100,
=100000;
(9)372-197+128,
=372+128-197,
=500-200+3,
=303.
解析分析:(1)(3)(6)运用乘法分配律解答,(2)(5)依据减法性质解答,(4)按照先算括号里面的,再算括号外面的顺序解答,(7)依据加法性质解答,(8)运用乘法交换律以及乘法结合律解答,(9)运用加法交换律解答.
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.