题目内容
简便计算
722-301 | 235-190+165 | 986-169-131 |
167+141+359+33 | 425+438+175 | 463-148 |
解:(1)722-301,
=700+22-(300+1),
=700-300+(22-1),
=400+21,
=421;
(2)235-190+165,
=(235+165)-190,
=400-(200-10),
=400-200+10,
=210;
(3)986-169-131,
=986-(169+131),
=986-300,
=686;
(4)167+141+359+33,
=(167+33)+(141+359),
=200+500,
=700;
(5)425+438+175,
=(425+175)+438,
=600+438,
=1038;
(6)463-148,
=440+23-(140+8),
=(440-140)+(23-8),
=300+15,
=315.
分析:(1)把722看作700+22,把301看作300+1,然后运用减法的性质以及加法交换律与结合律简算;
(2)(4)(5)运用加法交换律和结合律简算;
(3)运用减法的性质简算;
(6)把463看作440+23,把148看作140+8,然后运用减法的性质以及加法交换律与结合律简算.
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.
=700+22-(300+1),
=700-300+(22-1),
=400+21,
=421;
(2)235-190+165,
=(235+165)-190,
=400-(200-10),
=400-200+10,
=210;
(3)986-169-131,
=986-(169+131),
=986-300,
=686;
(4)167+141+359+33,
=(167+33)+(141+359),
=200+500,
=700;
(5)425+438+175,
=(425+175)+438,
=600+438,
=1038;
(6)463-148,
=440+23-(140+8),
=(440-140)+(23-8),
=300+15,
=315.
分析:(1)把722看作700+22,把301看作300+1,然后运用减法的性质以及加法交换律与结合律简算;
(2)(4)(5)运用加法交换律和结合律简算;
(3)运用减法的性质简算;
(6)把463看作440+23,把148看作140+8,然后运用减法的性质以及加法交换律与结合律简算.
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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