七、小学四则混合运算计算法则：（四则运算指加、减、乘、除四种运算）

1、在没有括号的算式里，只有加减法或只有乘除法的，都要从左往右按顺序运算；

2、在没有括号的算式里，有乘除法和加减法的，要先算乘除再算加减；

3、算式里有括号的要先算括号里面的，再算括号外面的。（有小括号、中括号、大括号的，要先算小括号里的，再算中括号里的，再算大括号里的。）

推荐阅读：
Integration Tests Using PHPUnit to Ensure Your Website is Workin　 Find Out the Longest Arithmetic Sequence in Array Using Dynamic 　 Find Numbers with Even Number of Digits using the Reduce Functio　 How to Convert Blogging Leads into Sales　 24 Things Your WordPress Form Plugin Can Do Besides Create A Con　 Blogging and Finance Management: How to Secure Your Financial Fu　 9 Easy-to-Use SEO Tips to Boost Your Site’s Visibility Today　 How to Land Guest Blogging Opportunities in Under an Hour　 Tips For Creating An Education Blog That Will Attract Followers　 What Is Data Blending, And What Does It Have To Do With SEO?