题目内容
脱式计算:
150÷25+72×3
1+0.45÷0.9-0.75
1-×÷
×[8.6÷(3.7+)]
解:(1)150÷25+72×3,
=6+216,
=222;
(2)1+0.45÷0.9-0.75,
=1+0.5-0.75,
=1.5-0.75,
=0.75;
(3)1-×÷,
=1-××,
=1-××,
=1-×,
=1-,
=;
(4)×[8.6÷(3.7+)],
=×[8.6÷4.3],
=×2,
=.
分析:(1)同时运算除法和乘法,再算加法;
(2)先算除法,再算加法,最后算减法;
(3)先把除法变成乘法,运用乘法交换律简算,最后算减法;
(4)先算小括号里面的加法,再算中括号里面的除法,最后算括号外的乘法.
点评:本题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定律进行简便计算.
=6+216,
=222;
(2)1+0.45÷0.9-0.75,
=1+0.5-0.75,
=1.5-0.75,
=0.75;
(3)1-×÷,
=1-××,
=1-××,
=1-×,
=1-,
=;
(4)×[8.6÷(3.7+)],
=×[8.6÷4.3],
=×2,
=.
分析:(1)同时运算除法和乘法,再算加法;
(2)先算除法,再算加法,最后算减法;
(3)先把除法变成乘法,运用乘法交换律简算,最后算减法;
(4)先算小括号里面的加法,再算中括号里面的除法,最后算括号外的乘法.
点评:本题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定律进行简便计算.
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