🔢 展开式（数位分解）计算器Expanded Form Calculator
把整数或小数按数位展开成加法式、乘法式（数字 × 位值）和 10 的幂形式，小数部分同时给出分数形式；支持负数和最多 40 位数字，按字符串精确处理不丢位。Write a whole number or decimal in expanded form — as a sum of place values, as digit × place value, and with powers of ten, plus fraction form for the decimal places. Negative numbers and up to 40 digits are handled exactly as text.
使用说明与常见问题How-to & FAQ
「展开式（数位分解）计算器」是什么？What is the Expanded Form Calculator tool?
把整数或小数按数位展开成加法式、乘法式（数字 × 位值）和 10 的幂形式，小数部分同时给出分数形式；支持负数和最多 40 位数字，按字符串精确处理不丢位。Write a whole number or decimal in expanded form — as a sum of place values, as digit × place value, and with powers of ten, plus fraction form for the decimal places. Negative numbers and up to 40 digits are handled exactly as text.
如何使用「展开式（数位分解）计算器」？How do I use the Expanded Form Calculator tool?
在「展开式（数位分解）计算器」中，填写「数字」等参数，结果会随输入实时计算并显示在下方。In the Expanded Form Calculator: Fill in "Number"; results are recalculated instantly as you type.
什么是展开式？What is expanded form?
展开式把一个数写成各数位位值之和。例如 4321.05 = 4000 + 300 + 20 + 1 + 0.05，也可写成 4 × 1000 + 3 × 100 + 2 × 10 + 1 × 1 + 5 × 0.01，或 4 × 10³ + 3 × 10² + 2 × 10¹ + 1 × 10⁰ + 5 × 10⁻²。值为 0 的数位省略。Expanded form writes a number as the sum of its place values. For example 4321.05 = 4000 + 300 + 20 + 1 + 0.05, or 4 × 1000 + 3 × 100 + 2 × 10 + 1 × 1 + 5 × 0.01, or 4 × 10³ + 3 × 10² + 2 × 10¹ + 1 × 10⁰ + 5 × 10⁻². Zero digits are left out.
能输入多大的数？How big a number can I enter?
最多 40 位有效数字（前导零和小数末尾的零不计）。数字按字符串逐位处理，不经过浮点运算，所以长数字也不会丢位。逗号只能作千位分隔（如 1,000,200），像 1,5 这样的写法会被拒绝，以免和小数混淆。Up to 40 significant digits (leading zeros and trailing decimal zeros don't count). Digits are processed as text, not floating point, so long numbers keep every digit. Commas are accepted only as thousands separators (1,000,200); something like 1,5 is rejected so it can't be mistaken for a decimal.
负数怎么展开？How are negative numbers expanded?
先展开它的绝对值，再在整体前加负号，例如 -506 = -(500 + 6)。The absolute value is expanded and the whole sum is negated, e.g. -506 = -(500 + 6).
「展开式（数位分解）计算器」免费吗？需要注册吗？Is the Expanded Form Calculator free? Do I need an account?
「展开式（数位分解）计算器」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 Expanded Form 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.