题目内容
计算下面各题.
×4÷ | +×13 | ×÷× |
-0.3× | 68×(-) | [1-(+)]÷. |
解:(1)×4÷,
=×4×,
=1;
(2)+×13,
=×(13+1),
=×14,
=3;
(3)×÷×,
=×××,
=;
(4)-0.3×,
=-×,
=-,
=;
(5)68×(-),
=68×-68×,
=60-18,
=42;
(6)[1-(+)]÷,
=[1-]÷,
=×4,
=.
分析:(1)(3)把除法改为乘法,约分即可;
(2)(5)运用乘法分配律简算;
(4)把小数化为分数先算乘法,再算减法;
(6)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此题考查了分数的四则混合运算,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.
=×4×,
=1;
(2)+×13,
=×(13+1),
=×14,
=3;
(3)×÷×,
=×××,
=;
(4)-0.3×,
=-×,
=-,
=;
(5)68×(-),
=68×-68×,
=60-18,
=42;
(6)[1-(+)]÷,
=[1-]÷,
=×4,
=.
分析:(1)(3)把除法改为乘法,约分即可;
(2)(5)运用乘法分配律简算;
(4)把小数化为分数先算乘法,再算减法;
(6)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此题考查了分数的四则混合运算,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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