The sum$-$of$-$the$-$years digits $($SYD$)$ depreciation method:

A$.$ divides the depreciable value of an asset by its useful life to calculate depreciation expense.

B$.$ calculates the annual depreciation expense factor based on current output $($numerator$)$ divided by the total expected output over the useful life of the asset $($denominator$)$ and multiplies this factor by the depreciable value.

C$.$ divides the depreciable value of an asset by its useful life, doubles this result, and applies it to the assets remaining book value to calculate depreciation expense.

D$.$ calculates the annual depreciation expense factor based on the current year $($numerator$)$ divided by the sum of the useful life of the asset $($denominator$)$ and multiplies this factor by the depreciable value.