When data is "gathered" around a particular value.
For example: for the values 2, 6, 7, 8, 8.5, 10, 15, there is a cluster around the value 8.
数学辞典收录了1200条数学词条,基本涵盖了常用数学知识及数学英语单词词组的翻译及用法,是数学学习的有利工具。