Answer :
The highway department needs to put up 55 mile marker signs for the entire 53-mile highway, including one at the start and one at the end.
To solve this, we add the starting marker and the ending marker to the number of miles between them. Since there is one sign per mile, we get a sign for each of the 53 miles plus one at the beginning and one at the end for a total of:
53 (for each mile) + 1 (start) + 1 (end) = 55 mile markers.
Therefore, the highway department needs to put up 55 mile marker signs for the entire stretch of the highway.
53 total signs but not including the one at the end and the beginning 51 signs