If a weekday newspaper has approximately 500,000 subscribers,then an article in that newspaper has approximately 500,000 impressions.

An impression is defined as each time an individual sees or is exposed to an advertisement or article, regardless of whether or not they actually read it. Therefore, if a newspaper has 500,000 subscribers, then an article in that newspaper has the potential to reach all 500,000 of those subscribers and thus generate approximately 500,000 impressions.