Explanation:
just look at the line.
the distance between 2 whole numbers is split into 1/2, then each 1/2 again into 1/2 = 1/4, and then every 1/4 again into 1/2 = 1/8. so, in total, we are dealing with 8 segments of 1/8 length.
now we count : we have a full 1, and then on the way to 2 we get only 5 units of 1/8 = 5/8.
so, in total the number is
1 5/8