The National Park Service is building a 16-mile hiking trail. They will post a sign every mile along the trail, including one at the end. There will not bea sign posted at the beginning of the trail. How many signs will they post along the trail?

The awnser will be 16 because the beginning if the trail is not the beginning of a mile

We can draw this figure out by using a '-' for a mile of the trail, and a 'l' for a sign. There will not be a sign at the beginning, but there will be a sign at the end. So let's draw that:

-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l-l

By counting the amount of 'l's in the figure above, we are then able to determine that there will be 16 signs posted.