Scaling of probability of magnification. The curves show the area in the source plane with magnification greater than a certain value due to millilenses in the lens plane. Solid lines are for millilenses in regions of the lens plane where the macromodel magnification is positive (positive parity), while dashed lines are for millilenses in regions of the lens plane with negative macromodel magnification (negative parity). Blue curves are for a millilens with mass 10³ M_⊙ and macromodel magnification ±23, red curves are for millilenses with mass 4 × 10³ M_⊙ and macromodel magnification ±23. Green curves are for a millilens with mass 10³ M_⊙ and macromodel magnification ±46. The black vertical line indicates a factor of four difference. The probability of magnification scales linearly with the mass of the millilens and quadratically with the macromodel magnification.