Table 1 Comparison between measured tip-sample Interaction values in case of pristine nanoparticle samples, as shown in figure 4 and single particle expectation values as theoretically derived from equations 4 and 7. For the single particle calculations the experimental tip-sample parameters have been used (m_m = 3*10⁻19 Am²; m_t = 1*10⁻16 Am²; H = 20 nm; A_{SP =} 85 nm; z₀ ≈52 nm). The third column contains the ratio between experimental data and single particle expectation values, allowing for a direct estimation of the number of particles involved in the interaction

From: “Magnetic Force Microscopy and Energy Loss Imaging of Superparamagnetic Iron Oxide Nanoparticles”