To calculate the depreciation use double the straight line rate .for example ,suppose a business has an asset with a cost of 1000,  100 salvage value for 5 years useful life    ....the u need to calculate
Depreciation expense is calculated utilizing either a straight line depreciation method or an accelerated depreciation method. The straight line method calculates depreciation by spreading the cost evenly over the life of the fixed asset. Accelerated depreciation methods such as declining balance and sum of years digits calculate depreciation by expensing a large part of the cost at the beginning of the life of the fixed asset.