脱式计算 ①4995-51×42②5670÷(315÷15)③32×(86-37)④241+2961÷47.
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解:(1)4995-51×42,
=4995-2142,
=2853;
(2)5670÷(315÷15),
=5670÷21,
=270;
(3)32×(86-37),
=32×49,
=1568;
(4)241+2961÷47,
=241+63,
=304.
解析分析:(1)先算乘法,再算减法,(2)先算小括号里的除法,再算括号外的除法,(3)先算小括号里的减法,再算括号外的乘法,(4)先算除法,再算加法.
点评:此题考查了整数四则混合运算的顺序,注意有小括号的运算顺序.