On January 1, Y4, Aylmer Corporation bought machinery for $800,000. They used double declining balance depreciation for this asset, with an estimated life of eight years, and an estimated $200,000 residual value. At the beginning of Y7, Aylmer decided to change to the straight-line method of depreciation for this equipment, and treated the change as a change in estimate. For calendar Y7, the depreciation expense for this machinery is