题目内容
计算下面各题,能简算的要简算.
7.28++2.72+
(+)÷
168.1÷(4.3×2-0.4)
36×+36×0.375
+÷.
解:(1)7.28++2.72+,
=(7.28+2.72)+(+),
=10+1,
=11;
(2)(+)÷,
=(+)×24,
=×24+×24,
=9+4,
=13;
(4)168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
(5)36×+36×0.375,
=36×(+0.375),
=36×(0.625+0.375),
=36×1,
=36;
(6)+÷,
=+×,
=+,
=.
分析:(1)运用加法交换律与结合律简算;
(2)把除法改为乘法,运用乘法分配律简算;
(3)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;
(4)运用乘法分配律简算,同时把分数化为小数;
(5)先算除法,再算加法.
点评:考查了四则混合运算,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.
=(7.28+2.72)+(+),
=10+1,
=11;
(2)(+)÷,
=(+)×24,
=×24+×24,
=9+4,
=13;
(4)168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
(5)36×+36×0.375,
=36×(+0.375),
=36×(0.625+0.375),
=36×1,
=36;
(6)+÷,
=+×,
=+,
=.
分析:(1)运用加法交换律与结合律简算;
(2)把除法改为乘法,运用乘法分配律简算;
(3)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;
(4)运用乘法分配律简算,同时把分数化为小数;
(5)先算除法,再算加法.
点评:考查了四则混合运算,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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