The term 'PART OF A CAPITAL-GAIN CALCULATION' can be summarized by the crossword solution 'BASIS' (5 letters). BASIS is a term used in accounting and finance to refer to the original value of an asset for tax purposes. It is used to calculate capital gains or losses when the asset is sold. The BASIS is usually the purchase price of the asset, but it can also include other costs associated with the asset such as improvements or repairs.