The following formula is involved in the calculation of net income multiplier values:

Net income multiplier (NIM):
where P is the purchase price and NOI is the net operating income.

The following references can be used to cite this net income multiplier (nim) calculator:
 Soper, D.S. (2017) "Net Income Multiplier (NIM) Calculator (Online Software)", http://www.danielsoper.com/fincalc. 
 Siegel, J. and Shim, J. (1997). "Schaum's Quick Guide to Business Formulas", New York, NY: McGrawHill. 