Past exam of the short options paper shared by Prelims and Parts A and B of the physics course of the University of Oxford / 2017 / S16 / 3 / 4 / Solution

Magnetic pressure is the field energy density $P_B=B_f^2/(2{\mu }_0)$. Using the preceding final field gives $\boxed{P_B\simeq 2.6\times 10^{13}\mathrm{Pa}\simeq 260\mathrm{Mbar}}$. This uses the compressed field, not the initial 36 T field; substituting the latter would omit the square of the already squared convergence amplification.