好像可以理解为四舍五入(韦伯字典好像是这样解释的)到第几位，‘what is the hundreds digits of the interger z, 条件2. z rounded to the nearest hundred is 9300’就是把十位数及以后的全部不要了，只保留到百位数。 Round: Merriam-Webster's Dictionary的解释：to express as a round number often used with off *11.3572 rounded off to two decimal places becomes 11.36* Longman Dictionary的解释：3、to change an exact figure to the nearest whole number
round something ↔ off to
例句：Prices are rounded off to the nearest dollar. round somebody/something ↔ up phrasal verb
3、to increase an exact figure to the next highest whole number
see also round down | 
