题目内容
(2008?西藏)用简便方法计算(要写出主要的简算过程)
①15.07-2-14+3.86 | ②1.25×37×8×10 |
③999×99 | ④360+702+360+360 |
分析:①运用减法的性质简算;
②运用乘法交换律与结合律简算;
③把999看作1000-1,运用乘法分配律简算;
④此算式种有3个360,可把原式变为360×3+702,先算乘法,再算加法.
②运用乘法交换律与结合律简算;
③把999看作1000-1,运用乘法分配律简算;
④此算式种有3个360,可把原式变为360×3+702,先算乘法,再算加法.
解答:解:①15.07-2-14+3.86,
=(15.07+3.86)-(2+14),
=18.93-16,
=2.93;
②1.25×37×8×10,
=(1.25×8)×(37×10),
=10×370,
=370;
③999×99,
=(1000-1)×99,
=1000×99-99×1,
=99000-99,
=98901;
④360+702+360+360,
=360×3+702,
=1080+702,
=1782.
=(15.07+3.86)-(2+14),
=18.93-16,
=2.93;
②1.25×37×8×10,
=(1.25×8)×(37×10),
=10×370,
=370;
③999×99,
=(1000-1)×99,
=1000×99-99×1,
=99000-99,
=98901;
④360+702+360+360,
=360×3+702,
=1080+702,
=1782.
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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