算术题生成

算术题生成面向三到六年级的混合运算练习：两步或三步、带不带括号都能控制，数值上限可以到 1000。相比口算，它更强调「先乘除后加减」和括号优先级的判断，适合在学完运算顺序之后做巩固。 A mixed-operation generator for upper primary grades. Choose two or three steps, switch brackets on or off, and allow numbers up to 1000. It drills order of operations and bracket precedence rather than plain mental arithmetic.

主要功能上，步数支持两步与三步；括号有三种口径——不带括号、随机带括号、每道都带括号；数值范围可选 100 或 1000 以内；题量可选 6、12、20 题。生成时会先算一遍结果，除不尽、出现负数或数值过大的表达式直接丢弃重出，所以页面上每道题的答案都是整数。 Steps can be two or three. Brackets come in three modes: none, random, or always. Number range is up to 100 or 1000, and you can request 6, 12 or 20 problems. Every expression is evaluated while generating; remainders, negative results and oversized numbers are discarded, so every printed answer is a whole number.

优势亮点在于题干干净、结果可控：不出现小数和分数，不用边做边猜答案对不对；题目与答案都在本地生成，不上传内容；打印时自动隐藏设置面板与页面装饰，只输出算式和三栏排版，一页能放十几道题。 The output stays clean and predictable: no decimals or fractions, no guessing whether an answer works out. Everything is generated locally, and printing hides the settings panel so only the problems and their three-column layout remain.

适用人群与场景：三年级以上刚开始接触混合运算的学生；需要每天布置几道递等式练习的老师；给小升初做运算速度训练的家庭；以及想把现成题目贴进讲义或课件的培训老师。 Good for pupils meeting mixed operations for the first time, teachers assigning a few chain-calculation problems daily, families drilling speed before middle school, and tutors pasting problems into handouts.

需要说明的边界：为了保证整数答案，乘除参与时会压低数值，偶尔会出现数字偏小的题；它不判分、不出竖式，也不保存练习记录。 Limits: to keep answers whole, multiplication and division pull values down, so some problems use smaller numbers. It does not grade, does not produce long division layout, and keeps no history.

使用方式也很直接：先定步数与括号，再把范围调到 100 或 1000，最后选题量；点「生成新题」换一批，点「显示答案」核对，点「打印」得到三栏练习纸。整个过程在本机完成，断网也能继续出题。 Using it is straightforward: set steps and brackets, choose the 100 or 1000 range, then pick a count. New problems refreshes, Show answers checks, and Print gives the three-column sheet. Everything runs locally, so it keeps working offline.