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If you had placed more assets into service than just the flooring, then a different convention (other than half-year) may have been used. For the depreciation details you shared, using 20% of the basis for the first year is correct. It is the subsequent years that will be different amounts.
For property with a 5-year recovery period, being depreciated using MACRS, half-year convention/200DB, 20% of the basis is calculated for the first year the property is in service. Subsequent years will be 32%, 19.2%, 11.52%, 11.52%, and 5.76%.
See the following excerpt from the IRS Publication 946 How to Depreciate Property:
