Magnetic field at a dipole (how many atoms surround the dipole?)

pearapple

1. The problem statement, all variables and given/known data
Consider a paramagnetic material. The magnetic field generated by each dipole in the material is 1/30 T.

What is the magnetic field at a given spin, due to the presence of nearby spins?


2. Relevant equations


3. The attempt at a solution
So I need to multiply 1/30 by however many spins are nearby.

But I'm not sure how many this would be. If the paramagnetic material is in a crystal, then there are 8 dipoles around it, but there are also dipoles below and underneath it. Which ones do I count as 'nearby'? What is the total number of dipoles?

Also, I'm measuring the magnetic field at one particular dipole. So the magnetic field from that dipole doesn't count, right?