Slide 17 of 59
Notes:
The integral of the magnetic field around the surface of the star must be a constant and the radius collapses from 7e8 m to 1e4m. Thus the ratio of the magnetic fields of the neutron star to the Sun is equivalent to the ratio of their radii squared… and this is approximately 5e9. So the magnetic field of a 1 solar mass neutron star is 5 billion times that of the Sun.
