The rules for using numbers in academic writing vary among academic disciplines. The conventions described here are for NON-TECHNICAL academic prose where numbers are not a significant focus. Scientific and technical writing will have their own conventions and students should consult a manual dedicated to those standards. The main rules about the use of numbers in standard academic writing are about:学术写作中，不同的科目对数字书写的要求不同。本文所指规则主要适用于一般的非技术性文章，此类文章中，数字本身并非重点。科技写作自有一套标准，读者在书写此类文章时，应当查阅专门的手册。一般地，标准学术写作中数字的应用要求是：

1. When to write numbers in words一、知道何时使用英文字母书写数字；2. How to avoid confusion with numbers in a sentence二、知道如何避免数字导致的表意不清；3. When to use digits for numbers三、知道何时使用阿拉伯数字；4. How to write numbers correctly四、知道如何正确书写数字。

GRAMMAR CHECKERS will not help you with the acceptable presentation of numbers in academic writing. You need to know and use the conventions for writing numbers correctly when you are writing and proofreading your work.注：“拼写检查”类软件不会检测学术文章中数字的书写是否规范，因此在写作和校对时，作者应当知晓此类规范，并在写作中加以注意。

1. When to write numbers in words一、使用英文字母书写数字

• Write in words one or two-word numbers, rounded numbers and ordinal numbers（一）一到两个单词的数、取整的数、序数For general academic writing, you need to write these numbers in words: all numbers under one hundred (e.g. ninety-nine) rounded numbers (e.g. four hundred, two thousand, six million) and ordinal numbers (e.g. third, twenty-fifth). Exceptions: See 3. When to use digits for numbers在常规的学术写作中，以下情况中的数字需要用英文字母书写：100以下的数（如：九十五）、取整的数（如：四百、两千、六百万）、序数（如：第三、第二十五）。例外情况：请见“三、使用阿拉伯数字”

Examples如：-- The country had been at war for twenty-five years. (number under 100)1.这个国家已经打了二十五年的仗。（100以下的数）-- Over four hundred