Measures and scales (orders of magnitude)

Whenever we read news articles we are bombarded with series of numbers, usually large ones ("The government spend millions of dollars on helping the poor").
The same happens when reading scientific materials ("The earth is millions of kilometers away from the Sun.").

What do those numbers mean? What do they represent? Most of the time, we are missing a sense of scale to evaluate the true significance of such numbers.

This group is about trying to make a sense of those numbers. It is also a way to put into perspective what the article we are reading is actually saying.