There are 6 divisions of space between each integer 1, 0, -1, -2. Three of these divisions make ½ and four make ⅔. So we start at -2½ shown in blue and we move 4 divisions to the right and end up at the red line. If we count the number of divisions to the left of -1 we get 5. Therefore, the result of the sum -2½ + ⅔ = -1⅚.