Given below is the formula for calculating depreciation in this method.
R = 1 – (S/C)1/n X 100
Where R = Rate of Depreciation (in %),
n = Useful life of the asset (in years)
S = Scrap value at the end of useful life of the asset
C= Cost of the asset
R = 1 – (256/10000)1/4 X 100
R = (1 - .4) x 100 = 60%