题目内容
计算下面各题.
①1.3-3.79+9.7-6.21
②3.64÷4+4.36×25%
③÷[+(1-)]
④+〔÷(+)〕
解:①1.3-3.79+9.7-6.21,
=(1.3+9.7)-(3.79+6.21),
=11-10,
=1;
②3.64÷4+4.36×25%,
=3.64×+4.36×,
=(3.64+4.36)×,
=8×,
=2;
③[+(1-)]÷,
=[+]×,
=×,
=;
④+〔÷(+),
=+[÷],
=+×,
=+,
=.
分析:①运用加法交换律与结合率以及减法的性质简算;
②把除法改为乘法,把百分数化为分数,运用乘法分配律简算;
③④先算小括号内的,最后算括号外的.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
=(1.3+9.7)-(3.79+6.21),
=11-10,
=1;
②3.64÷4+4.36×25%,
=3.64×+4.36×,
=(3.64+4.36)×,
=8×,
=2;
③[+(1-)]÷,
=[+]×,
=×,
=;
④+〔÷(+),
=+[÷],
=+×,
=+,
=.
分析:①运用加法交换律与结合率以及减法的性质简算;
②把除法改为乘法,把百分数化为分数,运用乘法分配律简算;
③④先算小括号内的,最后算括号外的.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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