Field times radius gives the speed-square that closes a circular orbit. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Radius 4 needs speed-square 4
The field at this radius is 1. Multiplying field by radius gives speed-square 4. Dividing back by radius returns acceleration 1.
1⋅4=4,rv2=1
Radius 2 needs speed-square 8
The field at this radius is 4. Multiplying field by radius gives speed-square 8. Dividing back by radius returns acceleration 4.
4⋅2=8,rv2=4
Radius 1 needs speed-square 16
The field at this radius is 16. Multiplying field by radius gives speed-square 16. Dividing back by radius returns acceleration 16.
16⋅1=16,rv2=16
Circular speed-square is a radius budget, not a separate guess
Each row starts from the checked field. The needed speed-square is field times radius, and the orbit check divides by the same radius to get back to the field.