If I understand the question correctly you are looking for the mid point between 4 and -6. There are 11 numbers that fall between 4 and -6. They are
4,3,2,1,0,-1,-2,-3,-4,-5 and -6
Which number falls exactly in the middle? There are 5 numbers on each side and 1 in the middle
4,3,2,1 and 0 above the mid point
-1 in the middle or at the mid point
and -2,-3,-4,-5 and -6 below the mid point
-1 would be your mid point.