用简便方法计算下面各题.3.06-2.5+1.943.8+3.98+6.029.53-(4.53+2.4)76-9.36-30.642.29+3.7+6.71+6.

发布时间:2020-07-30 20:31:26

用简便方法计算下面各题. 3.06-2.5+1.943.8+3.98+6.029.53-(4.53+2.4)76-9.36-30.642.29+3.7+6.71+6.33.25-0.13-1.25-0.87.

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解:(1)3.06-2.5+1.94,
=3.06+1.94-2.5,
=5-2.5,
=2.5;

(2)3.8+3.98+6.02,
=3.8+(3.98+6.02),
=3.8+10,
=13.8;

(3)9.53-(4.53+2.4),
=9.53-4.53-2.4,
=5-2.4,
=2.6;

(4)76-9.36-30.64,
=76-(9.36+30.64),
=76-40,
=36;(5)2.29+3.7+6.71+6.3,
=(2.29+6.71)+(3.7+6.3),
=9+10,
=19;

(6)3.25-0.13-1.25-0.87,
=3.25-1.25-(0.13+0.87),
=2-1,
=1.
解析分析:(1)3.06-2.5+1.94,根据加法交换律据此进行简算;(2)3.8+3.98+6.02,运用加法结合律进行简算;(3)9.53-(4.53+2.4),根据减法的运算性质进行简算;(4)76-9.36-30.64,根据减法的运算性质进行简算;(5)2.29+3.7+6.71+6.3,运用加法的交换律和结合律进行简算;(6)3.25-0.13-1.25-0.87,根据减法的运算性质进行简算.

点评:此题考查的目的是理解加法交换律、结合律的意义,加、减法的运算性质,并且能够灵活运用这些运算定律和运算性质进行简便计算.
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