table of contents recoverability of goodwill is measured at the reporting unit level and begins with a qualitative assessment to determine if it is more likely than not that the fair value of each reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test prescribed by gaap .for those reporting units where it is required , the first step compares the carrying amount of the reporting unit to its estimated fair value .if the estimated fair value of a reporting unit exceeds its carrying amount , goodwill of the reporting unit is not impaired and the second step of the impairment test is not necessary .to the extent that the carrying value of the reporting unit exceeds its estimated fair value , a second step is performed , wherein the reporting unit's carrying value of goodwill is compared to the implied fair value of goodwill .to the extent that the carrying value exceeds the implied fair value , impairment exists and must be recognized .the calculation of estimated fair value is based on two valuation techniques , a discounted cash flow model ( income approach ) and a market adjusted multiple of earnings and revenues ( market approach ) , with each method being weighted in the calculation .the implied fair value of goodwill is determined in the same manner as the amount of goodwill recognized in a business combination .the estimated fair value of the reporting unit is allocated to all of the assets and liabilities of the reporting unit ( including any unrecognized intangible assets ) as if the reporting unit had been acquired in a business combination and the fair value of the reporting unit , as determined in the first step of the goodwill impairment test , was the price paid to acquire that reporting unit .recoverability of other intangible assets with indefinite useful lives ( i.e .trademarks ) is determined on a relief from royalty methodology ( income approach ) , which is based on the implied royalty paid , at an appropriate discount rate , to license the use of an asset rather than owning the asset .the present value of the after-tax cost savings ( i.e .royalty relief ) indicates the estimated fair value of the asset .any excess of the carrying value over the estimated fair value is recognized as an impairment loss equal to that excess .intangible assets such as patents , customer-related intangible assets and other intangible assets with finite useful lives are amortized on a straight-line basis over their estimated economic lives .the weighted-average useful lives approximate the following: .
[['customer relationships', '25', 'years'], ['trademarks', '25', 'years'], ['completed technology/patents', '10', 'years'], ['other', '25', 'years']]
recoverability of intangible assets with finite useful lives is assessed in the same manner as property , plant and equipment as described above .income taxes : for purposes of the company 2019s consolidated financial statements for periods prior to the spin-off , income tax expense has been recorded as if the company filed tax returns on a stand-alone basis separate from ingersoll rand .this separate return methodology applies the accounting guidance for income taxes to the stand-alone financial statements as if the company was a stand-alone enterprise for the periods prior to the spin-off .therefore , cash tax payments and items of current and deferred taxes may not be reflective of the company 2019s actual tax balances prior to or subsequent to the spin-off .cash paid for income taxes for the year ended december 31 , 2015 was $ 80.6 million .the income tax accounts reflected in the consolidated balance sheets as of december 31 , 2015 and 2014 include income taxes payable and deferred taxes allocated to the company at the time of the spin-off .the calculation of the company 2019s income taxes involves considerable judgment and the use of both estimates and allocations .deferred tax assets and liabilities are determined based on temporary differences between financial reporting and tax bases of assets and liabilities , applying enacted tax rates expected to be in effect for the year in which the differences are expected to reverse .the company recognizes future tax benefits , such as net operating losses and tax credits , to the extent that realizing these benefits is considered in its judgment to be more likely than not .the company regularly reviews the recoverability of its deferred tax assets considering its historic profitability , projected future taxable income , timing of the reversals of existing temporary differences and the feasibility of its tax planning strategies .where appropriate , the company records a valuation allowance with respect to a future tax benefit .product warranties : standard product warranty accruals are recorded at the time of sale and are estimated based upon product warranty terms and historical experience .the company assesses the adequacy of its liabilities and will make adjustments as necessary based on known or anticipated warranty claims , or as new information becomes available. .

Question: what is the difference between the weighted average useful lives of trademarks and patents , in number of years?\\n
Answer: 15
Explanation: it is the variation between those weighted-average useful lives .