🔢 四则运算顺序（逐步计算）Order of Operations Calculator
输入算式，按运算顺序（括号 → 乘方 → 乘除从左到右 → 加减从左到右，即 PEMDAS/BODMAS）一步一步算出结果，每步只做一次运算；用分数精确计算，同时给出小数。Enter an expression to evaluate it step by step in the order of operations — parentheses, exponents, multiplication and division left to right, then addition and subtraction left to right (PEMDAS/BODMAS) — one operation per step, exactly with fractions and with a decimal too.
使用说明与常见问题How-to & FAQ
「四则运算顺序（逐步计算）」是什么？What is the Order of Operations Calculator tool?
输入算式，按运算顺序（括号 → 乘方 → 乘除从左到右 → 加减从左到右，即 PEMDAS/BODMAS）一步一步算出结果，每步只做一次运算；用分数精确计算，同时给出小数。Enter an expression to evaluate it step by step in the order of operations — parentheses, exponents, multiplication and division left to right, then addition and subtraction left to right (PEMDAS/BODMAS) — one operation per step, exactly with fractions and with a decimal too.
如何使用「四则运算顺序（逐步计算）」？How do I use the Order of Operations Calculator tool?
在「四则运算顺序（逐步计算）」中，填写「算式（支持 + − × ÷ * / ^ 和括号）」等参数，结果会随输入实时计算并显示在下方。In the Order of Operations Calculator: Fill in "Expression (+ − × ÷ * / ^ and parentheses)"; results are recalculated instantly as you type.
运算顺序是什么？What is the order of operations?
先算括号里的，再算乘方，然后从左到右算乘法和除法，最后从左到右算加法和减法。英文常用口诀 PEMDAS 或 BODMAS。注意乘除是同一级、按从左到右的顺序，所以 8 ÷ 2 × 4 = 16，而不是 1。Parentheses first, then exponents, then multiplication and division from left to right, then addition and subtraction from left to right — PEMDAS or BODMAS. Multiplication and division share a level and go left to right, so 8 ÷ 2 × 4 = 16, not 1.
−3^2 是 9 还是 −9？Is −3^2 equal to 9 or −9?
按通常的约定乘方先于负号，所以 −3^2 = −(3^2) = −9；要算 (−3)² 请加括号。连续乘方从右往左：2^3^2 = 2^9 = 512。By the usual convention the exponent comes before the minus sign, so −3^2 = −(3^2) = −9; write (−3)^2 for 9. Stacked exponents go right to left: 2^3^2 = 2^9 = 512.
2(3+4) 这种省略乘号的写法可以吗？Can I write 2(3+4)?
可以，括号前省略的乘号按普通乘法处理，与 × 同级、从左到右。有些计算器会让这种「隐含乘法」优先，所以像 6 ÷ 2(1+2) 这样的式子有歧义，最好写清楚。Yes — a number before a parenthesis is ordinary multiplication, at the same level as ×, left to right. Some calculators give implied multiplication priority, so expressions like 6 ÷ 2(1+2) are ambiguous; it is best to write them clearly.
计算精度如何？How precise are the results?
每一步都用分数（BigInt）精确计算，没有浮点误差；只有最后附带的小数值是按双精度浮点数四舍五入显示的。Every step is computed exactly with fractions (BigInt), so there is no floating-point error; only the decimal shown next to the result is rounded from a double-precision number.
「四则运算顺序（逐步计算）」免费吗？需要注册吗？Is the Order of Operations Calculator free? Do I need an account?
「四则运算顺序（逐步计算）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Order of Operations Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.