A ballet dancer performs pirouettes, rotating at: 1.5, 2.5, and 3.5 revolutions about a vertical axis while she is airborne. The dancer leaps in an "open" position with an initial moment of inertia of 𝐼₀ and a rotational frequency of 𝑓₀ = 1.0 rev/s. When the dancer pulls in their limbs towards their body, the inertia is reduced to 𝐼 and spins at frequency of 𝑓 before extending their limbs outwards once again before landing back on the ground. What is the change in the angular momentum during the dancer's pirouette? Neglect air resistance.