Question

Find the length of a line segment with end points of -9 and 7

Answer 1

If the segment begins at -9 and ends at 7, it will have a length of 17.

-9, -8, -7, -6, -5, -4, -3, -2, -1, 0,  1, 2 , 3, 4, 5, 6, 7 (Imagine this is the line segment, you can see there are 17 numbers on the line.)