🔣 数字各位和计算Digit Sum Calculator
计算任意长度整数各位数字之和、数字根（反复求和至一位）、交错和，并判断能否被 3、9、11 整除。Digit sum of any length number, its digital root (repeated sum), alternating sum, and divisibility by 3, 9 and 11.
使用说明与常见问题How-to & FAQ
「数字各位和计算」是什么？What is the Digit Sum Calculator tool?
计算任意长度整数各位数字之和、数字根（反复求和至一位）、交错和，并判断能否被 3、9、11 整除。Digit sum of any length number, its digital root (repeated sum), alternating sum, and divisibility by 3, 9 and 11.
如何使用「数字各位和计算」？How do I use the Digit Sum Calculator tool?
在「数字各位和计算」中，填写「整数（任意位数）」等参数，结果会随输入实时计算并显示在下方。In the Digit Sum Calculator: Fill in "Whole number (any length)"; results are recalculated instantly as you type.
计算精度如何？How precise are the results?
「数字各位和计算」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Digit Sum Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「数字各位和计算」免费吗？需要注册吗？Is the Digit Sum Calculator free? Do I need an account?
「数字各位和计算」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 Digit Sum 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.