To get the number in the white sector of each circle:

1. We have to first add all the 3 digits in the green sectors of the circle

2. Then divide the sum by 2.

For Instance:

1] 32 + 24 + 48 = 104

104/2 = 52

2] 23 + 35 + 46 = 104

104/2 = 52

3] 16 + 38 + 54 = 108

108/2 = 54

**4] 27 + 33 + 42 = 102**

102/2 = 51.