The following formula is involved in the calculation of actual cash values:

Actual cash value:
where P is the original purchase price of the item, CA is the current age of the item in years, and EL is the item's expected life in years.

The following references can be used to cite this actual cash value calculator:
 Soper, D.S. (2018) "Actual Cash Value 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. 