Syntax: DB(C, S, L, N, M)
C = Initial cost of asset
S = Salvage value of asset
L = Number of periods over which the asset is depreciating (life)
N = Number of periods over which to calculate the depreciation
M = (Optional) Number of months in the first year. Assumed to be 12 if omitted.
DB returns the fixed-declining real depreciation of an asset for a specified period.
DB(40000, 100, 6, 3, 2) = 8323.1198
Excel function: N/A