You can make your own: To make buttermilk, use 1 cup milk and 1 tablespoon lemon juice or white vinegar. Allow it to sit for a few minutes. If you do purchase buttermilk and have extra, freeze it in 1 cup containers or in Ziplock bags. You can also purchase powdered buttermilk in grocery stores.
Straight-line depreciation allows an equal portion of the laptop's cost to be claimed in each year over the total depreciation period. If the cost of the computer was $1,000, for example, then $200 a year can be included in the company's total depreciation amount each year for five years.
In the case of an LCD TV with a five-year useful life, that proportion in the first year would be 5/15 (5 useful years/5+4+3+2+1). First year depreciation assuming a $2,500 depreciating value would be $833 (2,500 x 5/15). Second year depreciation would be $667 (2,500 x 4/15).