# head coefficient and volume coefficient for centrifugal pump

If I need to calculate the head coefficient using $$c_h=\dfrac{gH}{N^2D^2}$$ and the volume coefficient using $$c_q= \dfrac{v}{ND^3}$$ while keeping $$N$$ (impeller rotational speed in rpm), how can I make the units cancel out and have a dimensionless answer?

I am measuring $$D$$ (impeller diameter in meters), $$g$$ (gravity m/s^2), $$H$$ (total pressure head in meters), $$V$$ (volumetric flow rate in m/s).

I made it dimensionless by changing RPM to 1/s, however I have been asked to keep RPM and change the other units, can someone plz help.