Answers at the beginning of 2019, robotics inc. acquired a manufacturing facility for $12.3 million. $9.3 million of the purchase price was allocated to the building. depreciation for 2019 and 2020 was calculated using the straight-line method, a 20-year useful life, and a $1.3 million residual value. in 2021, the estimates of useful life and residual value were changed to 15 total years and $530,000, respectively.